drm/radeon/kms/pm: add asic specific callbacks for setting power state (v2)

(v2) Add evergreen vbl checks

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/evergreen_reg.h b/drivers/gpu/drm/radeon/evergreen_reg.h
index f7c7c96..9dba6d9 100644
--- a/drivers/gpu/drm/radeon/evergreen_reg.h
+++ b/drivers/gpu/drm/radeon/evergreen_reg.h
@@ -166,6 +166,7 @@
 /* CRTC blocks at 0x6df0, 0x79f0, 0x105f0, 0x111f0, 0x11df0, 0x129f0 */
 #define EVERGREEN_CRTC_CONTROL                          0x6e70
 #       define EVERGREEN_CRTC_MASTER_EN                 (1 << 0)
+#define EVERGREEN_CRTC_STATUS                           0x6e8c
 #define EVERGREEN_CRTC_UPDATE_LOCK                      0x6ed4
 
 #define EVERGREEN_DC_GPIO_HPD_MASK                      0x64b0