drm/radeon: add get_allowed_info_register for CIK

Registers that can be fetched from the info ioctl.

Tested-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/cikd.h b/drivers/gpu/drm/radeon/cikd.h
index c648e19..4870df8 100644
--- a/drivers/gpu/drm/radeon/cikd.h
+++ b/drivers/gpu/drm/radeon/cikd.h
@@ -2088,6 +2088,8 @@
 #	define CLK_OD(x)				((x) << 6)
 #	define CLK_OD_MASK				(0x1f << 6)
 
+#define UVD_STATUS					0xf6bc
+
 /* UVD clocks */
 
 #define CG_DCLK_CNTL			0xC050009C