drm/radeon/kms: add new asic struct for rv6xx (v4)
drm/radeon/kms: add new asic struct for rv6xx (v4)

Has a different dpm controller than r600.

v2: rebase on gpu reset changes
v3: rebase on get_xclk changes
v4: update rptr/wtpr callbacks

Signed-off-by: Alex Deucher <08dc22c6156113f2deff178e35e3ed9b24d6af9e@amd.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs