drm/radeon/r600: add missing license and comments to r600_blit_shaders.c

drm/radeon/r600: add missing license and comments to r600_blit_shaders.c

R6xx+ cards need to use the 3D engine to blit data which requires
quite a bit of hw state setup.  Rather than pull the whole 3D driver
(which normally generates the 3D state) into the DRM, we opt to use
statically generated state tables.  The regsiter state and shaders
were hand generated to support blitting functionality.  See the 3D
driver or documentation for descriptions of the registers and
shader instructions.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>