drm/radeon: add initial rs690 support to drm.

This adds support for configuring the RS690 GART.

Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --cc drivers/char/drm/drm_pciids.h
Simple merge

diff --cc drivers/char/drm/radeon_cp.c
Simple merge

diff --cc drivers/char/drm/radeon_drv.h
Simple merge