ARM: dts: sun5i: q8-common: Enable USB-based WiFi

The early A13 Q8 tablets all use a Realtek WiFi module connected to
USB1. The module is powered by AXP209's LDO3 at 3.3V.

Move the related settings from sun5i-a13-q8-tablet.dts to
sun5i-q8-common.dtsi, for all q8-based tablets.

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