ARM64: dts: meson-gx-p23x-q20x: enable the USB controller

All S905D (GXL) and S912 (GXM) reference boards (namely these are
P230, P231, Q200 and Q201) provide USB connectors.
This enables the USB controller on these boards to make the USB ports
actually usable.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>