RDS/IB: Use SLAB_HWCACHE_ALIGN flag for kmem_cache_create()

We are *definitely* counting cycles as closely as DaveM, so
ensure hwcache alignment for our recv ring control structs.

Signed-off-by: Andy Grover <andy.grover@oracle.com>

net/rds/ib_recv.c

@@ -1051,13 +1051,13 @@ int __init rds_ib_recv_init(void)
 
 	rds_ib_incoming_slab = kmem_cache_create("rds_ib_incoming",
 					sizeof(struct rds_ib_incoming),
-					0, 0, NULL);
+					0, SLAB_HWCACHE_ALIGN, NULL);
 	if (!rds_ib_incoming_slab)
 		goto out;
 
 	rds_ib_frag_slab = kmem_cache_create("rds_ib_frag",
 					sizeof(struct rds_page_frag),
-					0, 0, NULL);
+					0, SLAB_HWCACHE_ALIGN, NULL);
 	if (!rds_ib_frag_slab)
 		kmem_cache_destroy(rds_ib_incoming_slab);
 	else