drm/i915/panel: setup pwm backlight based on connector type

Use the connector type instead of VBT directly to decide which backlight
mechanism to use on VLV/CHV. (Indirectly, this is the same thing, but
hides the VBT use.)
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1458125015-7931-5-git-send-email-jani.nikula@intel.com

drivers/gpu/drm/i915/intel_panel.c

@@ -1743,7 +1743,7 @@ intel_panel_init_backlight_funcs(struct intel_panel *panel)
 		panel->backlight.get = pch_get_backlight;
 		panel->backlight.hz_to_pwm = pch_hz_to_pwm;
 	} else if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
-		if (dev_priv->vbt.has_mipi) {
+		if (connector->base.connector_type == DRM_MODE_CONNECTOR_DSI) {
 			panel->backlight.setup = pwm_setup_backlight;
 			panel->backlight.enable = pwm_enable_backlight;
 			panel->backlight.disable = pwm_disable_backlight;