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/file.c b/fs/btrfs/file.c
index 83abd27..80eabe8 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -191,9 +191,9 @@
 	}
 	while (1) {
 		if (!split)
-			split = alloc_extent_map(GFP_NOFS);
+			split = alloc_extent_map();
 		if (!split2)
-			split2 = alloc_extent_map(GFP_NOFS);
+			split2 = alloc_extent_map();
 		BUG_ON(!split || !split2);
 
 		write_lock(&em_tree->lock);