Losing arbitration is normal in a CAN-bus network, it means that a higher
priority frame is being send and the pending message will be retried later.
Hence most driver only increment arbitration_lost, but the sun4i driver also
incremeants tx_error, causing errors to be reported on a normal functioning
CAN-bus. So stop counting them as errors.

Fixes: 0738eff1 ("can: Allwinner A10/A20 CAN Controller support - Kernel module")
Signed-off-by: Jeroen Hofstee <jhofstee@victronenergy.com>
Link: https://lore.kernel.org/r/20201127095941.21609-1-jhofstee@victronenergy.com
[mkl: split into two seperate patches]
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>