TTY: pty, fix pty counting in "/proc/sys/kernel/pty/nr"

Excuse me, my persistence.

But, I don't understand,
what for, "pty" driver, invoked tty_driver_remove_tty(), only for call its own function(pty_unix98_remove). In commit: 24d406a6bf736f7aebdc8fa0f0ec86e0890c6d24.

Thank you.
Ilya.