can: ems_usb: ems_usb_rx_err(): fix {rx,tx}_errors statistics

can: ems_usb: ems_usb_rx_err(): fix {rx,tx}_errors statistics

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

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

Fixes: 702171adeed3 ("ems_usb: Added support for EMS CPC-USB/ARM7 CAN/USB interface")
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://patch.msgid.link/20241122221650.633981-12-dario.binacchi@amarulasolutions.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>