drm/edid: Add 6 bpc quirk for SDC panel in Lenovo B50-80

Another panel that reports "DFP 1.x compliant TMDS" but it supports 6bpc
instead of 8 bpc.

Apply 6 bpc quirk for the panel to fix it.

BugLink: https://bugs.launchpad.net/bugs/1788308
Cc: <stable@vger.kernel.org> # v4.8+
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20180823055332.7723-1-kai.heng.feng@canonical.com

drivers/gpu/drm/drm_edid.c

@@ -116,6 +116,9 @@ static const struct edid_quirk {
 	/* CPT panel of Asus UX303LA reports 8 bpc, but is a 6 bpc panel */
 	{ "CPT", 0x17df, EDID_QUIRK_FORCE_6BPC },
 
+	/* SDC panel of Lenovo B50-80 reports 8 bpc, but is a 6 bpc panel */
+	{ "SDC", 0x3652, EDID_QUIRK_FORCE_6BPC },
+
 	/* Belinea 10 15 55 */
 	{ "MAX", 1516, EDID_QUIRK_PREFER_LARGE_60 },
 	{ "MAX", 0x77e, EDID_QUIRK_PREFER_LARGE_60 },