drm/msm/mdp4: Call custom round_pixclk helper only if the encoder type is TMDS

The mdp_kms round_pixclk op creates problems when we have more
interfaces in use. It calls the DTV encoder's helper by default.

Check on encoder type and call the corresponding encoder's
func meant for rounding pixel clock. DSI and LVDS don't require
rounding, so just return rate in their case.
Signed-off-by: NArchit Taneja <architt@codeaurora.org>
Signed-off-by: NRob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/mdp/mdp4/mdp4_kms.c

@@ -169,7 +169,14 @@ static long mdp4_round_pixclk(struct msm_kms *kms, unsigned long rate,
 		struct drm_encoder *encoder)
 {
 	/* if we had >1 encoder, we'd need something more clever: */
-	return mdp4_dtv_round_pixclk(encoder, rate);
+	switch (encoder->encoder_type) {
+	case DRM_MODE_ENCODER_TMDS:
+		return mdp4_dtv_round_pixclk(encoder, rate);
+	case DRM_MODE_ENCODER_LVDS:
+	case DRM_MODE_ENCODER_DSI:
+	default:
+		return rate;
+	}
 }
 
 static void mdp4_preclose(struct msm_kms *kms, struct drm_file *file)