drm/panel: panel-simple: Fix proper bpc for AM-1280800N3TZQW-T00H

AM-1280800N3TZQW-T00H panel support 8 bpc not 6 bpc as per
recent testing in i.MX8MM platform.

Fix it.

Fixes: bca684e69c4c ("drm/panel: simple: Add AM-1280800N3TZQW-T00H")
Signed-off-by: Jagan Teki <[e-mail]>
Reviewed-by: Robert Foss <[e-mail]>
Signed-off-by: Robert Foss <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

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

···
 static const struct panel_desc ampire_am_1280800n3tzqw_t00h = {
 	.modes = &ampire_am_1280800n3tzqw_t00h_mode,
 	.num_modes = 1,
-	.bpc = 6,
+	.bpc = 8,
 	.size = {
 		.width = 217,
 		.height = 136,