can: xilinx: Update proper TEC and REC in xcan_get_berr_counter

This patch updates the proper Transmit error counter(TEC)
and Receive error counter(REC) in xcan_get_berr_counter routine.

Signed-off-by: Kedareswara rao Appana <appanad@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>