cloning repo

git clone https://www.github.com/frank-w/openwrt
cd openwrt

installing depencies:

./scripts/feeds update -a
./scripts/feeds install -a

configuration:

make menuconfig
=> Target System (MediaTek Ralink ARM)
=> Subtarget (MT7623)
=> Target Profile (Bpi Banana Pi R2) 
=> Target Images
   => tar.gz

edit Makefile to change Kernel from 4.19 to 5.4 (already done in my repo)

nano target/linux/mediatek/Makefile
=> KERNEL_PATCHVER:=5.4
make -j8 kernel_menuconfig