arm64: dts: a64-olinuxino: Enable RTL8723BS WiFi

Enable RTL8723BS WiFi chip on a64-olinuxino board:
- WiFi SDIO interface is connected to MMC1
- WiFi REG_ON pin connected to gpio PL2: attach to mmc-pwrseq
- WiFi HOST_WAKE pin connected to gpio PL3

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>