netbsd-7 DRMKMS on Thinkpad T420s

[David Brownlee <abs%absd.org@localhost>]

I thought I'd try DRMKMS X11 under netbsd-7.

Installed 201412240730Z from nyftp, everything seemed to go fine but X
failed to start.

Dropped in a current kernel from 201412260830Z and X started up fine.
Managed to crash it under firefox, so disabling acceleration will be
something to try next.

In case its of interest - dmesg & Xorg log from the 7 and current boot below:

http://sync.absd.org/DRMKMS-2014-12/Xorg.0.log.7
http://sync.absd.org/DRMKMS-2014-12/Xorg.0.log.head
http://sync.absd.org/DRMKMS-2014-12/dmesg.7
http://sync.absd.org/DRMKMS-2014-12/dmesg.head