Add to your drivers/net/wireless/realtek/Kconfig:
source "drivers/net/wireless/realtek/rtl8822bu/Kconfig"
source "drivers/net/wireless/realtek/rtl8812au/Kconfig"
source "drivers/net/wireless/realtek/rtl8188eus/Kconfig"
And add to your drivers/net/wireless/realtek/Makefile:
obj-$(CONFIG_RTL8822BU) += rtl8822bu/
obj-$(CONFIG_88XXAU) += rtl8812au/
obj-$(CONFIG_RTL8188EU) += rtl8188eus/
Only 1 driver may be added inline/built-in of rtl8812au or rtl8822bu The rtl8188eus must always be a module.