mb/siemens/mc_ehl: Switch to 16 MB ROM and provide a flashmap

There is a 16 MB flash chip on mc_ehl. Set the ROM size accordingly and
provide a flashmap for partitioning. Select the used flashmap on variant
level to allow different layouts for different variants.

Change-Id: I694729ad98f91e27308220903c49e7cb7fc436b4
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56035
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>

src/mainboard/siemens/mc_ehl/Kconfig

@@ -1,7 +1,7 @@
 config BOARD_SIEMENS_BASEBOARD_MC_EHL
 	def_bool n
 	select SOC_INTEL_ELKHARTLAKE
-	select BOARD_ROMSIZE_KB_32768
+	select BOARD_ROMSIZE_KB_16384
 	select DRIVERS_I2C_GENERIC
 	select HAVE_SPD_IN_CBFS
 	select HAVE_ACPI_TABLES

src/mainboard/siemens/mc_ehl/mc_ehl.fmd

@@ -0,0 +1,11 @@
+FLASH @0xff000000 CONFIG_ROM_SIZE {
+	SI_ALL 0x400000 {
+		SI_DESC 0x1000
+		SI_ME 0x3ff000
+	}
+	SI_BIOS 0xc00000 {
+		FMAP 0x200
+		RW_MRC_CACHE 0x10000
+		COREBOOT(CBFS)
+	}
+}

src/mainboard/siemens/mc_ehl/variants/mc_ehl1/Kconfig

@@ -0,0 +1,7 @@
+if BOARD_SIEMENS_MC_EHL1
+
+config FMDFILE
+	string
+	default "src/mainboard/\$(CONFIG_MAINBOARD_DIR)/mc_ehl.fmd"
+
+endif # BOARD_SIEMENS_MC_EHL1