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/r600d.h b/drivers/gpu/drm/radeon/r600d.h
index a0dbf1f..c6857e8 100644
--- a/drivers/gpu/drm/radeon/r600d.h
+++ b/drivers/gpu/drm/radeon/r600d.h
@@ -485,6 +485,7 @@
 #define		TC_L2_SIZE(x)					((x)<<5)
 #define		L2_DISABLE_LATE_HIT				(1<<9)
 
+#define	VC_ENHANCE					0x9714
 
 #define	VGT_CACHE_INVALIDATION				0x88C4
 #define		CACHE_INVALIDATION(x)				((x)<<0)