I checkout u-boot tag: v2023.10
https://github.com/u-boot/u-boot/tree/v2023.10
run build:
```shell
export
STAGING_DIR=/home/foo/openwrt-toolchain-22.03.4-ramips-mt7621_gcc-11.2.0_musl.Linux-x86_64/
make mt7621_rfb_defconfig
make
CROSS_COMPILE=/home/foo/openwrt-toolchain-22.03.4-ramips-mt7621_gcc-11.2.0_musl.Linux-x86_64/toolchain-mipsel_24kc_gcc-11.2.0_musl/bin/mipsel-openwrt-linux-musl-
```
build failed:
```shell
CC spl/common/spl/spl.o
AR spl/common/spl/built-in.o
LD spl/u-boot-spl
OBJCOPY spl/u-boot-spl-nodtb.bin
COPYspl/u-boot-spl.bin
SYM spl/u-boot-spl.sym
MKIMAGE u-boot.img
MKIMAGE u-boot-dtb.img
LZMAu-boot.bin.lzma
MKIMAGE u-boot-lzma.img
BINMAN .binman_stamp
Image 'u-boot-spl-ddr' is missing external blobs and is non-functional:
stage_bin
/binman/u-boot-spl-ddr/stage_bin (mt7621_stage_sram.bin):
Missing blob
Some images are invalid
make: *** [Makefile:1115: .binman_stamp] Error 103
```
Is there a step I'm missing that's causing this?
