can: rx-offload: can_rx_offload_irq_finish(): directly call napi_schedule()

Instead of calling can_rx_offload_schedule() call napi_schedule()
directly. As this was the last use of can_rx_offload_schedule() remove
this helper function.

Link: https://lore.kernel.org/r/20210724204745.736053-3-mkl@pengutronix.de


Tested-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>