lib: remove empty return types from doxygen comments

Recent versions of doxygen (1.9.4 and newer) complain about
documented return types for functions that don't return anything.

This patch removes these return types to fix build errors similar
to this one:
[..]
Generating doc/api/doxygen with a custom command
FAILED: doc/api/html
/usr/bin/python3 /path/to/doc/api/generate_doxygen.py doc/api/html
  /usr/bin/doxygen doc/api/doxy-api.conf
/root/dpdk/lib/eal/include/rte_bitmap.h:324: error: found documented
  return type for rte_bitmap_prefetch0 that does not return anything
  (warning treated as error, aborting now)
[..]

Tested with doxygen versions: 1.8.13, 1.8.17, 1.9.1, and 1.9.4.

Signed-off-by: Ali Alnubani <alialnu@nvidia.com>
Acked-by: Stephen Hemminger <stephen@networkplumber.org>

lib/eal/include/rte_bitmap.h

@@ -327,8 +327,6 @@ rte_bitmap_reset(struct rte_bitmap *bmp)
  *   Handle to bitmap instance
  * @param pos
  *   Bit position
- * @return
- *   0 upon success, error code otherwise
  */
 static inline void
 rte_bitmap_prefetch0(struct rte_bitmap *bmp, uint32_t pos)

lib/eal/include/rte_hexdump.h

@@ -27,8 +27,6 @@ extern "C" {
 *		This is the buffer address to print out.
 * @param len
 *		The number of bytes to dump out
-* @return
-*		None.
 */
 
 extern void
@@ -45,8 +43,6 @@ rte_hexdump(FILE *f, const char * title, const void * buf, unsigned int len);
 *		This is the buffer address to print out.
 * @param len
 *		The number of bytes to dump out
-* @return
-*		None.
 */
 
 void

lib/fib/rte_fib.h

@@ -124,8 +124,6 @@ rte_fib_find_existing(const char *name);
  * @param fib
  *   FIB object handle created by rte_fib_create().
  *   If fib is NULL, no operation is performed.
- * @return
- *   None
  */
 void
 rte_fib_free(struct rte_fib *fib);

lib/fib/rte_fib6.h

@@ -115,8 +115,6 @@ rte_fib6_find_existing(const char *name);
  * @param fib
  *   FIB object handle created by rte_fib6_create().
  *   If fib is NULL, no operation is performed.
- * @return
- *   None
  */
 void
 rte_fib6_free(struct rte_fib6 *fib);

lib/hash/rte_thash.h

@@ -329,8 +329,6 @@ rte_thash_find_existing(const char *name);
  *
  * @param ctx
  *  Thash context
- * @return
- *  None
  */
 __rte_experimental
 void

lib/ipsec/rte_ipsec_sad.h

@@ -139,8 +139,6 @@ rte_ipsec_sad_find_existing(const char *name);
  *
  * @param sad
  *   pointer to the SAD object
- * @return
- *   None
  */
 void
 rte_ipsec_sad_destroy(struct rte_ipsec_sad *sad);

lib/lpm/rte_lpm.h

@@ -180,8 +180,6 @@ rte_lpm_find_existing(const char *name);
  * @param lpm
  *   LPM object handle
  *   If lpm is NULL, no operation is performed.
- * @return
- *   None
  */
 void
 rte_lpm_free(struct rte_lpm *lpm);

lib/lpm/rte_lpm6.h

@@ -73,8 +73,6 @@ rte_lpm6_find_existing(const char *name);
  * @param lpm
  *   LPM object handle
  *   If lpm is NULL, no operation is performed.
- * @return
- *   None
  */
 void
 rte_lpm6_free(struct rte_lpm6 *lpm);

lib/reorder/rte_reorder.h

@@ -116,8 +116,6 @@ rte_reorder_reset(struct rte_reorder_buffer *b);
  * @param b
  *   Pointer to reorder buffer instance.
  *   If b is NULL, no operation is performed.
- * @return
- *   None
  */
 void
 rte_reorder_free(struct rte_reorder_buffer *b);

lib/rib/rte_rib.h

@@ -265,8 +265,6 @@ rte_rib_find_existing(const char *name);
  * @param rib
  *   RIB object handle created with rte_rib_create().
  *   If rib is NULL, no operation is performed.
- * @return
- *   None
  */
 void
 rte_rib_free(struct rte_rib *rib);

lib/rib/rte_rib6.h

@@ -320,8 +320,6 @@ rte_rib6_find_existing(const char *name);
  * @param rib
  *   RIB object handle created with rte_rib6_create().
  *   If rib is NULL, no operation is performed.
- * @return
- *   None
  */
 void
 rte_rib6_free(struct rte_rib6 *rib);