vc4/hdmi: Fix Hsync and Vsync polarity changes

Polarity bits were only ever set and never cleared.
Make sure they can also be cleared.

Signed-off-by: Michiel Vanbiervliet <[email protected]>

Author: Michiiel

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -1897,7 +1897,8 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
 	spin_lock_irqsave(&vc4_hdmi->hw_lock, flags);
 
 	HDMI_WRITE(HDMI_VID_CTL,
-		   HDMI_READ(HDMI_VID_CTL) |
+		   (HDMI_READ(HDMI_VID_CTL) &~
+		   (VC4_HD_VID_CTL_VSYNC_LOW | VC4_HD_VID_CTL_HSYNC_LOW)) |
 		   VC4_HD_VID_CTL_ENABLE |
 		   VC4_HD_VID_CTL_CLRRGB |
 		   VC4_HD_VID_CTL_UNDERFLOW_ENABLE |