usb: dwc3: meson-g12a: fix device leaks at unbind

usb: dwc3: meson-g12a: fix device leaks at unbind

Make sure to drop the references taken to the child devices by
of_find_device_by_node() during probe on driver unbind.

Fixes: c99993376f72 ("usb: dwc3: Add Amlogic G12A DWC3 glue")
Cc: stable@vger.kernel.org	# 5.2
Cc: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20250724091910.21092-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>