drm/msm/adreno: add a2xx

derived from the a3xx driver and tested on the following hardware:
imx51-zii-rdu1 (a200 with 128kb gmem)
imx53-qsrb (a200)
msm8060-tenderloin (a220)

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Reviewed-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>