xfs: rename _zone variables to _cache

Now that we've gotten rid of the kmem_zone_t typedef, rename the
variables to _cache since that's what they are.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>
diff --git a/fs/xfs/xfs_bmap_item.h b/fs/xfs/xfs_bmap_item.h
index 6af6b02..3fafd38 100644
--- a/fs/xfs/xfs_bmap_item.h
+++ b/fs/xfs/xfs_bmap_item.h
@@ -65,7 +65,7 @@ struct xfs_bud_log_item {
 	struct xfs_bud_log_format	bud_format;
 };
 
-extern struct kmem_cache	*xfs_bui_zone;
-extern struct kmem_cache	*xfs_bud_zone;
+extern struct kmem_cache	*xfs_bui_cache;
+extern struct kmem_cache	*xfs_bud_cache;
 
 #endif	/* __XFS_BMAP_ITEM_H__ */