drm/msm: drop A2xx and common headers

Now as the headers are generated during the build step, drop
pre-generated copies of the Adreno A2xx and common headers.

Signed-off-by: Dmitry Baryshkov <[email protected]>
Patchwork: https://patchwork.freedesktop.org/patch/585861/
Link: https://lore.kernel.org/r/[email protected]

Author: lumag