Revert "ubifs: Fix memory leak bug in alloc_ubifs_info() error path"

This reverts commit 9163e018.

At the point when ubifs_fill_super() runs, we have already a reference
to the super block. So upon deactivate_locked_super() c will get
free()'ed via ->kill_sb().

Cc: Wenwen Wang <wenwen@cs.uga.edu>
Fixes: 9163e018

 ("ubifs: Fix memory leak bug in alloc_ubifs_info() error path")
Reported-by: https://twitter.com/grsecurity/status/1180609139359277056
Signed-off-by: Richard Weinberger <richard@nod.at>
Tested-by: Romain Izard <romain.izard.pro@gmail.com>
Signed-off-by: Richard Weinberger <richard@nod.at>