drm/i915: Use RSEN instead of HTPLG for tfp410 monitor detection.

Presence detection of a digital monitor seems not to be reliable using
the HTPLG bit.

Dave Müller <dave.mueller@gmx.ch>

drivers/gpu/drm/i915/dvo_tfp410.c

@@ -208,7 +208,7 @@ static enum drm_connector_status tfp410_detect(struct intel_dvo_device *dvo)
 	uint8_t ctl2;
 
 	if (tfp410_readb(dvo, TFP410_CTL_2, &ctl2)) {
-		if (ctl2 & TFP410_CTL_2_HTPLG)
+		if (ctl2 & TFP410_CTL_2_RSEN)
 			ret = connector_status_connected;
 		else
 			ret = connector_status_disconnected;