soc/mediatek/mt8188: Enable ARM Trusted Firmware integration

Enable configuration to build with MT8186 arm-trusted-firmware drivers.

TEST=build pass
BUG=b:236331724

Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Change-Id: Id16405c84f6e0a2e21f95cc45babf85bd980b43e
Reviewed-on: https://review.coreboot.org/c/coreboot/+/67356
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Yidi Lin <yidilin@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/mediatek/mt8188/Kconfig b/src/soc/mediatek/mt8188/Kconfig
index 972170e..271a122 100644
--- a/src/soc/mediatek/mt8188/Kconfig
+++ b/src/soc/mediatek/mt8188/Kconfig
@@ -5,6 +5,7 @@
 	select ARCH_VERSTAGE_ARMV8_64
 	select ARCH_ROMSTAGE_ARMV8_64
 	select ARCH_RAMSTAGE_ARMV8_64
+	select ARM64_USE_ARM_TRUSTED_FIRMWARE
 	select HAVE_UART_SPECIAL
 	select SOC_MEDIATEK_COMMON
 	select FLASH_DUAL_IO_READ
diff --git a/src/soc/mediatek/mt8188/Makefile.inc b/src/soc/mediatek/mt8188/Makefile.inc
index 3f83cbc..d446d5a 100644
--- a/src/soc/mediatek/mt8188/Makefile.inc
+++ b/src/soc/mediatek/mt8188/Makefile.inc
@@ -47,6 +47,8 @@
 ramstage-y += ../common/sspm.c
 ramstage-y += ../common/usb.c usb.c
 
+BL31_MAKEARGS += PLAT=mt8188
+
 CPPFLAGS_common += -Isrc/soc/mediatek/mt8188/include
 CPPFLAGS_common += -Isrc/soc/mediatek/common/include