thread-unsafety problems as spl*() ones are NOP

[mokhi]

Hi.
in kbd.c there are many places spltty()/splx() used assuming it locks/unlocks.
though there is bug filed for this, and ive asked in #bsddev, Ive
preferred to ask and ensure it from here again.
As these functions are obsoleted now, this assumption is incorrect and
some places we have thread-unsafely which leads to security problems
(and/or for example double-free, etc)

can i use mutex/spin/lock/unlock under where assumed a lock/unlock by
using spltty()/splx() to patch it?

Thanks, Mokhi.