sunxi: video: HDMI: split VSYNC and HSYNC polarity settings

These are actually different bits, and since some monitors (Benq BL2420PT)
have modes with different HSYNC and VSYNC polarity, we should set them
independently

Tested on Pine64-LTS with Benq BL2420PT monitor.
Signed-off-by: NVasily Khoruzhick <anarsoul@gmail.com>
Reviewed-by: NAnatolij Gustschin <agust@denx.de>
Acked-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: NJagan Teki <jagan@openedev.com>

drivers/video/sunxi/sunxi_dw_hdmi.c

@@ -304,15 +304,11 @@ static int sunxi_dw_hdmi_enable(struct udevice *dev, int panel_bpp,
 
 	sunxi_dw_hdmi_lcdc_init(priv->mux, edid, panel_bpp);
 
-	/*
-	 * Condition in original code is a bit weird. This is attempt
-	 * to make it more reasonable and it works. It could be that
-	 * bits and conditions are related and should be separated.
-	 */
-	if (!((edid->flags & DISPLAY_FLAGS_HSYNC_HIGH) &&
-	      (edid->flags & DISPLAY_FLAGS_VSYNC_HIGH))) {
-		setbits_le32(&phy->pol, 0x300);
-	}
+	if (edid->flags & DISPLAY_FLAGS_HSYNC_LOW)
+		setbits_le32(&phy->pol, 0x200);
+
+	if (edid->flags & DISPLAY_FLAGS_VSYNC_LOW)
+		setbits_le32(&phy->pol, 0x100);
 
 	setbits_le32(&phy->ctrl, 0xf << 12);