fs/xfs: Remove NULL check before kmem_cache_destroy

kmem_cache_destroy already checks for null values.
Signed-off-by: Tim Hansen <devtimhansen@gmail.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/kmem.h

@@ -119,8 +119,7 @@ kmem_zone_free(kmem_zone_t *zone, void *ptr)
 static inline void
 kmem_zone_destroy(kmem_zone_t *zone)
 {
-	if (zone)
-		kmem_cache_destroy(zone);
+	kmem_cache_destroy(zone);
 }
 
 extern void *kmem_zone_alloc(kmem_zone_t *, xfs_km_flags_t);