vt: Fix deadlock on scroll-lock

Fixing the locking accidentally replaced a race in the scroll
lock handling with a deadlock. Turn it back into a race for
now.

The basic problem is that there are two paths into the tty
stop/start helpers. One via the tty layer ^S/^Q handling
where we need to take the kbd_event_lock and one via the
special keyboard handler for fn_hold where we already hold
it. Probably we need to split out into a separate LED lock
but for now just go back to the race as it's a bit close
to release.

Reported-by: Clemens Ladisch <clemens@ladisch.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>