net: dsa: microchip: move ksz8->shifts to ksz_common

This patch moves ksz8->shifts from ksz8795.c to ksz_common.c. The shifts
are dereferenced using dev->info->shifts.

Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>