btrfs: merge two superblock writing helpers

write_all_supers and write_ctree_super are almost equal, the parameter
'trans' is unused so we can drop it and have just one helper.

Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 43e7145..441a62c 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3695,7 +3695,7 @@ int btrfs_calc_num_tolerated_disk_barrier_failures(
 	return num_tolerated_disk_barrier_failures;
 }
 
-static int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
+int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
 {
 	struct list_head *head;
 	struct btrfs_device *dev;
@@ -3789,12 +3789,6 @@ static int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
 	return 0;
 }
 
-int write_ctree_super(struct btrfs_trans_handle *trans,
-		      struct btrfs_fs_info *fs_info, int max_mirrors)
-{
-	return write_all_supers(fs_info, max_mirrors);
-}
-
 /* Drop a fs root from the radix tree and free it. */
 void btrfs_drop_and_free_fs_root(struct btrfs_fs_info *fs_info,
 				  struct btrfs_root *root)