btrfs: fix for write_super_lockfs/unlockfs error handling

Commit c4be0c1dc4cdc37b175579be1460f15ac6495e9a added the ability for
write_super_lockfs to return errors, and renamed them to match.  But
btrfs didn't get converted.

Do the minimal conversion to make it compile again.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 file changed