usb: dwc3: meson-g12a: Add support for IRQ based OTG switching

Add support for the OTG ID change interrupt to switch between Host
and Device mode.

Tested on the Hardkernel Odroid-N2 board.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>