usb: dwc3: meson-g12a: specify phy names in soc data

To handle the variable USB2 PHY counts on GXL and GXM SoCs, add the
possible PHY names for each SoC in the compatible match data.

Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Hanjie Lin <hanjie.lin@amlogic.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>