drm/radeon/kms/legacy: set common regs to sane value

The DDX and radeonfb always set these regs to a sane value.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index 92bebc0..f3deb49 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -1046,6 +1046,7 @@
 				struct radeon_cs_packet *pkt,
 				unsigned idx);
 extern void r100_enable_bm(struct radeon_device *rdev);
+extern void r100_set_common_regs(struct radeon_device *rdev);
 
 /* rv200,rv250,rv280 */
 extern void r200_set_safe_registers(struct radeon_device *rdev);