mb/cavium to mb/foxcomm: Add SPDX license headers to Kconfig files

Change-Id: Ib100a677935cf3309a380952c35e9060e64433cb
Signed-off-by: Martin Roth <gaumless@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80591
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>

src/mainboard/emulation/qemu-i440fx/Kconfig.name

@@ -1,2 +1,4 @@
+## SPDX-License-Identifier: GPL-2.0-only
+
 config BOARD_EMULATION_QEMU_X86_I440FX
 	bool "QEMU x86 i440fx/piix4 (aka qemu -M pc)"