drm/radeon/dpm: fix r600_enable_sclk_control()

Actually program the correct register to enable
engine clock scaling control.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/r600_dpm.c b/drivers/gpu/drm/radeon/r600_dpm.c
index b88f54b..e5c860f 100644
--- a/drivers/gpu/drm/radeon/r600_dpm.c
+++ b/drivers/gpu/drm/radeon/r600_dpm.c
@@ -278,9 +278,9 @@
 void r600_enable_sclk_control(struct radeon_device *rdev, bool enable)
 {
 	if (enable)
-		WREG32_P(GENERAL_PWRMGT, 0, ~SCLK_PWRMGT_OFF);
+		WREG32_P(SCLK_PWRMGT_CNTL, 0, ~SCLK_PWRMGT_OFF);
 	else
-		WREG32_P(GENERAL_PWRMGT, SCLK_PWRMGT_OFF, ~SCLK_PWRMGT_OFF);
+		WREG32_P(SCLK_PWRMGT_CNTL, SCLK_PWRMGT_OFF, ~SCLK_PWRMGT_OFF);
 }
 
 void r600_enable_mclk_control(struct radeon_device *rdev, bool enable)