app/testpmd: remove unused struct member

The tx_queue member of the fwd_lcore struct is unused as it is already
part of the fwd_stream structure. Deleting helps improve code readability.

Signed-off-by: Kathleen Capella <kathleen.capella@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli@arm.com>
Acked-by: Thomas Monjalon <thomas@monjalon.net>

app/test-pmd/testpmd.h

@@ -247,7 +247,6 @@ struct fwd_lcore {
 	streamid_t stream_idx;   /**< index of 1st stream in "fwd_streams" */
 	streamid_t stream_nb;    /**< number of streams in "fwd_streams" */
 	lcoreid_t  cpuid_idx;    /**< index of logical core in CPU id table */
-	queueid_t  tx_queue;     /**< TX queue to send forwarded packets */
 	volatile char stopped;   /**< stop forwarding when set */
 };