arm-trusted-firmware-mediatek: add MT7981 sdmmc images

Add bl2 images for mt7981 sdmmc ddr4 devices.

Signed-off-by: Chukun Pan <amadeus@jmu.edu.cn>
Link: openwrt/openwrt#21000
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
(cherry picked from commit 3b14ace)

Author: aiamadeus

package/boot/arm-trusted-firmware-mediatek/Makefile

@@ -166,6 +166,14 @@ define Trusted-Firmware-A/mt7981-emmc-ddr4
   DDR_TYPE:=ddr4
 endef
 
+define Trusted-Firmware-A/mt7981-sdmmc-ddr4
+  NAME:=MediaTek MT7981 (SD card, DDR4)
+  BOOT_DEVICE:=sdmmc
+  BUILD_SUBTARGET:=filogic
+  PLAT:=mt7981
+  DDR_TYPE:=ddr4
+endef
+
 define Trusted-Firmware-A/mt7981-spim-nand-ddr4
   NAME:=MediaTek MT7981 (SPI-NAND via SPIM, DDR4)
   BOOT_DEVICE:=spim-nand
@@ -643,6 +651,7 @@ TFA_TARGETS:= \
 	mt7981-spim-nand-ubi-ddr4 \
 	mt7981-ram-ddr4 \
 	mt7981-emmc-ddr4 \
+	mt7981-sdmmc-ddr4 \
 	mt7981-spim-nand-ddr4 \
 	mt7981-cudy-tr3000-v1 \
 	mt7986-ram-ddr3 \