btrfs: drop gfp parameter from alloc_extent_map

pass GFP_NOFS directly to kmem_cache_alloc

Signed-off-by: David Sterba <dsterba@suse.cz>
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 7cdce82..6a3d537 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6694,7 +6694,7 @@
 	u64 start = extent_key->objectid - offset;
 	u64 end = start + extent_key->offset - 1;
 
-	em = alloc_extent_map(GFP_NOFS);
+	em = alloc_extent_map();
 	BUG_ON(!em);
 
 	em->start = start;