drm/panel: panel-simple: Fix proper bpc for ytc700tlag_05_201c

ytc700tlag_05_201c panel support 8 bpc not 6 bpc as per
recent testing in i.MX8MM platform.

Fix it.

Fixes: 7a1f4fa ("drm/panel: simple: Add YTC700TLAG-05-201C")
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210725174737.891106-1-jagan@amarulasolutions.com

Author: openedev

drivers/gpu/drm/panel/panel-simple.c

@@ -4166,7 +4166,7 @@ static const struct drm_display_mode yes_optoelectronics_ytc700tlag_05_201c_mode
 static const struct panel_desc yes_optoelectronics_ytc700tlag_05_201c = {
 	.modes = &yes_optoelectronics_ytc700tlag_05_201c_mode,
 	.num_modes = 1,
-	.bpc = 6,
+	.bpc = 8,
 	.size = {
 		.width = 154,
 		.height = 90,