drm/radeon: properly program gart on rv740, juniper, cypress, barts, hemlock

Need to program an additional VM register.  This doesn't not currently
cause any problems, but allows us to program the proper backend
map in a subsequent patch which should improve performance on these
asics.

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 79130bf..3dd43e7 100644
--- a/drivers/gpu/drm/radeon/evergreend.h
+++ b/drivers/gpu/drm/radeon/evergreend.h
@@ -452,6 +452,7 @@
 #define	MC_VM_MD_L1_TLB0_CNTL				0x2654
 #define	MC_VM_MD_L1_TLB1_CNTL				0x2658
 #define	MC_VM_MD_L1_TLB2_CNTL				0x265C
+#define	MC_VM_MD_L1_TLB3_CNTL				0x2698
 
 #define	FUS_MC_VM_MD_L1_TLB0_CNTL			0x265C
 #define	FUS_MC_VM_MD_L1_TLB1_CNTL			0x2660