quota: Fix memory leak when handling corrupted quota file

When checking corrupted quota file we can bail out and leak allocated
info structure. Properly free info structure on error return.

Reported-by:  <syzbot+77779c9b52ab78154b08@syzkaller.appspotmail.com>
Fixes: 11c514a9 ("quota: Sanity-check quota file headers on load")
Signed-off-by: Jan Kara <jack@suse.cz>