config: Save Star Labs coreboot oldconfigs

Store generated oldconfig files as the active coreboot configs and retain
their source defconfigs alongside them with the `_defconfig` suffix. This
makes both the resolved configuration and its concise input available for
review.

Signed-off-by: Thierry Laurion <insurgo@riseup.net>

Signed-off-by: Sean Rhodes <sean@starlabs.systems>

Author: tlaurion

config/coreboot-starlabs_adl_horizon.config

@@ -0,0 +1,17 @@
+CONFIG_USE_UEFI_VARIABLE_STORE=y
+CONFIG_SBOM=y
+CONFIG_VENDOR_STARLABS=y
+# CONFIG_POST_IO is not set
+CONFIG_HAVE_IFD_BIN=y
+CONFIG_EC_STARLABS_ADD_ITE_BIN=y
+# CONFIG_BOOTMEDIA_SMM_BWP is not set
+CONFIG_SOC_INTEL_COMMON_SPI_LOCKDOWN_SMM=y
+# CONFIG_INTEL_CHIPSET_LOCKDOWN is not set
+CONFIG_HAVE_ME_BIN=y
+CONFIG_LOCK_MANAGEMENT_ENGINE=y
+CONFIG_SMMSTORE=y
+CONFIG_BOOTMEDIA_LOCK_CONTROLLER=y
+CONFIG_MAINBOARD_SERIAL_NUMBER="HZ00000"
+CONFIG_PAYLOAD_LINUX=y
+CONFIG_PAYLOAD_FILE="@BOARD_BUILD_DIR@/bzImage"
+CONFIG_LINUX_INITRD="@BOARD_BUILD_DIR@/initrd.cpio.xz"