quota: fix infinite loop

If we fail to start a transaction when releasing dquot, we have to call
dquot_release() anyway to mark dquot structure as inactive.  Otherwise we
end in an infinite loop inside dqput().

Signed-off-by: Jan Kara <jack@suse.cz>
Cc: xb <xavier.bru@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>