siemens/mc_tcu3: Don't try to init unsupported panel type

The LCD panel type is read using 4 GPIOs. Of these 16 possible
combinations only 5 are supported right now. If the GPIO setting encodes
an unsupported panel type, there will be no matching hwinfo.hex in cbfs.
Therefore it makes no sense to try to initialize the DisplayPort-2-LVDS
converter. Leave the function instead in this case.

Change-Id: If8c67a3f5be762758d516c4939dd1de4ff1c8ba5
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/14743
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>

src/mainboard/siemens/mc_tcu3/lcd_panel.c

@@ -67,6 +67,7 @@ int setup_lcd_panel(void)
 		break;
 	default:
 		printk(BIOS_ERR, "LCD: No supported panel found.\n");
+		return 1;
 		break;
 	}