usb: dwc3: meson-gxl: add AXG compatible

Upstream Linux uses the "amlogic,meson-axg-usb-ctrl" for AXG SoCs.

This adds it to the compatible list for this driver.

Reported-by: Vyacheslav Bocharov <adeep@lexina.in>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Vyacheslav Bocharov <adeep@lexina.in>