xfs: remove xfs_buf_free_maps

xfs_buf_free_maps only has a single caller, so open code it there.  Stop
zeroing the b_maps pointer as the buffer is freed in the next line.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Carlos Maiolino <cem@kernel.org>

Author: Christoph Hellwig

fs/xfs/xfs_buf.c

@@ -88,23 +88,14 @@ xfs_buf_stale(
 	spin_unlock(&bp->b_lock);
 }
 
-static void
-xfs_buf_free_maps(
-	struct xfs_buf	*bp)
-{
-	if (bp->b_maps != &bp->__b_map) {
-		kfree(bp->b_maps);
-		bp->b_maps = NULL;
-	}
-}
-
 static void
 xfs_buf_free_callback(
 	struct callback_head	*cb)
 {
 	struct xfs_buf		*bp = container_of(cb, struct xfs_buf, b_rcu);
 
-	xfs_buf_free_maps(bp);
+	if (bp->b_maps != &bp->__b_map)
+		kfree(bp->b_maps);
 	kmem_cache_free(xfs_buf_cache, bp);
 }