can: sun4i_can: sun4i_can_err(): fix {rx,tx}_errors statistics

can: sun4i_can: sun4i_can_err(): fix {rx,tx}_errors statistics

The sun4i_can_err() function only incremented the receive error counter
and never the transmit error counter, even if the STA_ERR_DIR flag
reported that an error had occurred during transmission.

Increment the receive/transmit error counter based on the value of the
STA_ERR_DIR flag.

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/20241122221650.633981-11-dario.binacchi@amarulasolutions.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>