add yocto rootfs support in rootfs build shell script

guowenxue

2021-11-16 f073905c67250f13f550432a79ccc5dcc834a8c1

 bsp/bootloader/build.sh

@@ -95,6 +95,7 @@

    mkdir -p ${IMG_PATH}
    cp ${IMG_NAME} ${IMG_PATH}
    cp ${IMG_NAME} /tftp

    cd ${PRJ_PATH}
}