drm/radeon: add some additional 6xx/7xx/EG register init

- SMX_SAR_CTL0 needs to be programmed correctly to prevent
problems with memory exports in certain cases.
- VC_ENHANCE needs to be initialized on 6xx/7xx.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/evergreend.h b/drivers/gpu/drm/radeon/evergreend.h
index 2773039..b50b15c 100644
--- a/drivers/gpu/drm/radeon/evergreend.h
+++ b/drivers/gpu/drm/radeon/evergreend.h
@@ -503,6 +503,7 @@
 #define	SCRATCH_UMSK					0x8540
 #define	SCRATCH_ADDR					0x8544
 
+#define	SMX_SAR_CTL0					0xA008
 #define	SMX_DC_CTL0					0xA020
 #define		USE_HASH_FUNCTION				(1 << 0)
 #define		NUMBER_OF_SETS(x)				((x) << 1)