Define ATOMIC_LONG_INIT() in the LinuxKPI.

Obtained from:	kmacy @
MFC after:	1 week
Sponsored by:	Mellanox Technologies

sys/compat/linuxkpi/common/include/asm/atomic-long.h

@@ -35,6 +35,8 @@
 #include <sys/types.h>
 #include <machine/atomic.h>
 
+#define	ATOMIC_LONG_INIT(x)	{ .counter = (x) }
+
 typedef struct {
 	volatile long counter;
 } atomic_long_t;