drm/radeon/kms/pm: track current voltage (v2)

track the current voltage level and avoid setting it
if the requested voltage is already set.

v2: check voltage type before checking current voltage

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 2ad0e03..8e1d44c 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -748,6 +748,7 @@
 	int                     default_power_state_index;
 	u32                     current_sclk;
 	u32                     current_mclk;
+	u32                     current_vddc;
 	struct radeon_i2c_chan *i2c_bus;
 	/* selected pm method */
 	enum radeon_pm_method     pm_method;