Revert "tty: Fix ->pgrp locking in tiocspgrp()"

This reverts commit b029ee612ddbecbbd51a639ada87d0f4a2fad66a.

Apply a different backport later on that is more compatible to other
patches we need on this module.

Issue: SEC-3079
Change-Id: Ie32e1122322286736fec64d7361362fdc93c36d5
1 file changed