mb/samsung to mb/up: Add SPDX license headers to Kconfig files

Change-Id: Ied455ff29b151fb5f4bca26a189b1d4104d8cede
Signed-off-by: Martin Roth <gaumless@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80595
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/system76/adl/Kconfig.name

@@ -1,3 +1,5 @@
+## SPDX-License-Identifier: GPL-2.0-only
+
 config BOARD_SYSTEM76_DARP8
 	bool "darp8"