Third part wifi driver placed at external/wifi_driver to avoid submit to kernel.

wifi drivers here will be auto build with modules use:
./build.sh -K

You can use following commands to manaul build the certain wifi driver (e.g. rtl8822es):
cd exteranl/wifi_driver/
make ARCH=arm64 -C ../../kernel M=$PWD clean
make ARCH=arm64 -C ../../kernel M=$PWD
ko will generate at exteranl/wifi_driver/rtl8822es/8822es.ko

If exist both (e.g rtl8822es)
kernel/drivers/net/wireless/rockchip_wlan/rtl8822es (CONFIG_RTL8822ES=m)
and
exteranl/wifi_driver/rtl8822es/
will priority to use exteranl/wifi_driver/rtl8822es/