usb: chipidea: udc: implement get_frame

The chipidea udc core is capable of reading the current frame index from
hardware. This patch adds the get_frame callback to the driver.

Acked-by: Peter Chen <peter.chen@kernel.org>
Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
Link: https://lore.kernel.org/r/20220616194459.2981519-1-m.grzeschik@pengutronix.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>