This is a cleanup patch, no functional change intended. As
at91_irq_err_frame() is called from the IRQ handler move it in front
of the IRQ handler next to at91_irq_err().

Link: https://lore.kernel.org/all/20231005-at91_can-rx_offload-v2-20-9987d53600e0@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>