ARM: dts: sun9i: cubieboard4: Enable AP6330 WiFi

The board has a Ampak AP6330 WiFi/BT/FM module. Inside it is a Broadcom
BCM4330 WiFi/BT/FM combo IC. The WiFi portion is connected to mmc1, with
the enabling pin connected to PL2. The AC100 RTC provides a low power
clock signal.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>