Regression radeonkms r690 between r265233M and r268249

[J.R. Oldroyd]

I was using radeonkms on a laptop which has an RS690 flawlessly on
10-stable svn'd on 2014/05/01, r265233M.  X.org loads r300_dri.so and
all is well.

Updated to 10-stable on 2014/07/04, r268249 and now X.org fails to
detect the device and now loads swrast_dri.so instead.

Xorg.0.log files from both kernels are:

http://opal.com/jr/radeonkms/20140501-Xorg.0.log
http://opal.com/jr/radeonkms/20140704-Xorg.0.log

Logs show a difference with the 07/04 version not loading dri2 and
so loading shadowfb instead:

[    41.410] (II) RADEON(0): GPU accel disabled or not working, using shadowfb for KMS

All x.org ports were recompiled after the 07/04 update and, in fact,
these recompiled ports also work fine with the 05/01 kernel.old.  The
installed dri2.ko module was one of those recompiled.  Ports are
up-to-date.

	-jr