net: ldpaa_eth: fix the memory layout of the dpmac_get_counters() API

Each MC commands has a specific predefined memory layout that gets
interpreted by the firmware. The dpmac_get_counters() API memory layout
is wrong, thus the results returned by the command are incorrect.

Fix this by updating the offset of the counter field.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Ramon Fried <rfried.dev@gmail.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>