drm/radeon/kms/r600+: use voltage from requested clock mode (v3)

This fixes FDO bug #28375, it's kind of regression, so quite important to have
it for .35.

V2: Fix on RV770+ as well. All other chipsets have only one clock mode per
state.

V3: I'm out of luck today. Grepped for voltage in r*.c and missed evergreen.

agd5f: rebased

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r600.c b/drivers/gpu/drm/radeon/r600.c
index acec26b..7b55391 100644
--- a/drivers/gpu/drm/radeon/r600.c
+++ b/drivers/gpu/drm/radeon/r600.c
@@ -557,9 +557,10 @@
 
 void r600_pm_misc(struct radeon_device *rdev)
 {
-	int requested_index = rdev->pm.requested_power_state_index;
-	struct radeon_power_state *ps = &rdev->pm.power_state[requested_index];
-	struct radeon_voltage *voltage = &ps->clock_info[0].voltage;
+	int req_ps_idx = rdev->pm.requested_power_state_index;
+	int req_cm_idx = rdev->pm.requested_clock_mode_index;
+	struct radeon_power_state *ps = &rdev->pm.power_state[req_ps_idx];
+	struct radeon_voltage *voltage = &ps->clock_info[req_cm_idx].voltage;
 
 	if ((voltage->type == VOLTAGE_SW) && voltage->voltage) {
 		if (voltage->voltage != rdev->pm.current_vddc) {