mediatek: add mt7623 u-boot build for Banana Pi R2

For building full SD/eMMC images for Banana Pi R2 we'll want a u-boot
image built for that platform.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>

package/boot/uboot-mediatek/Makefile

@@ -27,7 +27,14 @@ define U-Boot/mt7622
   UBOOT_CONFIG:=mt7622_rfb
 endef
 
-UBOOT_TARGETS := mt7629 mt7622
+define U-Boot/mt7623n_bpir2
+  NAME:=Banana Pi R2 (mt7623)
+  BUILD_SUBTARGET:=mt7623
+  UBOOT_IMAGE:=u-boot.bin
+  UBOOT_CONFIG:=mt7623n_bpir2
+endef
+
+UBOOT_TARGETS := mt7629 mt7622 mt7623n_bpir2
 
 UBOOT_MAKE_FLAGS += $(UBOOT_IMAGE)
 

package/boot/uboot-mediatek/patches/005-update-bpir2-defconfig.patch

@@ -0,0 +1,14 @@
+diff --git a/configs/mt7623n_bpir2_defconfig b/configs/mt7623n_bpir2_defconfig
+index 6b9fbd7e22..fb2a004803 100644
+--- a/configs/mt7623n_bpir2_defconfig
++++ b/configs/mt7623n_bpir2_defconfig
+@@ -52,3 +52,9 @@ CONFIG_TIMER=y
+ CONFIG_WDT_MTK=y
+ CONFIG_LZMA=y
+ # CONFIG_EFI_LOADER is not set
++CONFIG_CMD_BOOTZ=y
++CONFIG_OF_LIBFDT_OVERLAY=y
++#enables savenenv-command
++CONFIG_ENV_IS_IN_MMC=y
++CONFIG_CMD_ASKENV=y
++CONFIG_ENV_SIZE=0x2000