can: sun4i_can: sun4i_can_err(): call can_change_state() even if cf is NULL

can: sun4i_can: sun4i_can_err(): call can_change_state() even if cf is NULL

Call the function can_change_state() if the allocation of the skb
fails, as it handles the cf parameter when it is null.

Additionally, this ensures that the statistics related to state error
counters (i. e. warning, passive, and bus-off) are updated.

Fixes: 0738eff14d81 ("can: Allwinner A10/A20 CAN Controller support - Kernel module")
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://patch.msgid.link/20241122221650.633981-3-dario.binacchi@amarulasolutions.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>