drm/radeon/dpm: re-enable cac control on SI

Now that the fixed point functions are fixed we
can re-enable cac support.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/si_dpm.c

@@ -2044,8 +2044,7 @@ static void si_initialize_powertune_defaults(struct radeon_device *rdev)
 	ni_pi->enable_sq_ramping = false;
 	si_pi->enable_dte = false;
 
-	/* XXX: fix me */
-	if (0/*si_pi->powertune_data->enable_powertune_by_default*/) {
+	if (si_pi->powertune_data->enable_powertune_by_default) {
 		ni_pi->enable_power_containment= true;
 		ni_pi->enable_cac = true;
 		if (si_pi->dte_data.enable_dte_by_default) {