can: at91_can: at91_chip_start(): don't disable IRQs twice

In at91_chip_start() first all IRQs are disabled, they do not have to
be disabled again at the end of the function before the requested IRQs
are enabled.

Remove the 2nd disable of all IRQs at the end of the function.

Link: https://lore.kernel.org/all/20231005-at91_can-rx_offload-v2-14-9987d53600e0@pengutronix.de


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>