ARM64: dts: meson-gxl-s905x-p212: enable the USB controller

ARM64: dts: meson-gxl-s905x-p212: enable the USB controller

All boards based on the P212 reference design (the P212 reference board
itself and the Khadas VIM) have USB connectors (in case of the Khadas
VIM the first port is exposed through the USB Type-C connector, the
second port is connected to a 4-port USB hub).
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>