Revert "tty: fix pid memleak in disassociate_ctty()"

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7PBYJ



--------------------------------

This reverts commit a2aa6b07.

Prepare to backport patch from mainline.

Signed-off-by: Yi Yang <yiyang13@huawei.com>