drm/bridge/synopsys: dw-hdmi: Enable workaround for v2.12a

It turns out that even new DW HDMI controllers exhibits same magenta
line issues as older versions.

Enable workaround for v2.12a.
Reviewed-by: NChen-Yu Tsai <wens@csie.org>
Signed-off-by: NJernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: NMaxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181104182705.18047-15-jernej.skrabec@siol.net

drivers/gpu/drm/bridge/synopsys/dw-hdmi.c

@@ -1664,6 +1664,7 @@ static void dw_hdmi_clear_overflow(struct dw_hdmi *hdmi)
 	case 0x131a:
 	case 0x132a:
 	case 0x201a:
+	case 0x212a:
 		count = 1;
 		break;
 	default: