mediatek: use DEVICE_DTC_FLAGS for BPi-R64

Make sure there is an extra 4kb of padding to apply device tree overlays
on the BPi-R64.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>

target/linux/mediatek/image/mt7622.mk

@@ -70,6 +70,7 @@ define Device/bananapi_bpi-r64
   DEVICE_DTS := mt7622-bananapi-bpi-r64
   DEVICE_DTS_OVERLAY := mt7622-bananapi-bpi-r64-pcie1 mt7622-bananapi-bpi-r64-sata
   DEVICE_PACKAGES := kmod-ata-ahci-mtk kmod-btmtkuart kmod-usb3 e2fsprogs mkf2fs f2fsck
+  DEVICE_DTC_FLAGS := --pad 4096
   ARTIFACTS := emmc-preloader.bin emmc-bl31-uboot.fip sdcard.img.gz snand-preloader.bin snand-bl31-uboot.fip
   IMAGES := sysupgrade.itb
   KERNEL_INITRAMFS_SUFFIX := -recovery.itb