mb/google/zork: Enable eMMC driver for edk2 payload

Several zork-based boards use eMMC for storage, so enable the edk2 eMMC
driver when using the edk2 payload.

TEST=build/boot google/zork (morphius, vilboz), verify internal boot
media (both eMMC and NVMe) functional with edk2 payload.

Change-Id: Ib7e98f309594554dbcf1ddd875d47c89bd9e0e44
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/81893
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/mainboard/google/zork/Kconfig

@@ -62,6 +62,7 @@ config BOARD_SPECIFIC_OPTIONS
 	select EC_GOOGLE_CHROMEEC_I2C_TUNNEL
 	select EC_GOOGLE_CHROMEEC_INCLUDE_SSFC_IN_FW_CONFIG
 	select EC_GOOGLE_CHROMEEC_SKUID
+	select EDK2_PCO_MMIO_EMMC if EDK2_REPO_MRCHROMEBOX
 	select ELOG
 	select ELOG_BOOT_COUNT
 	select ELOG_GSMI