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

This patch moves the ksz8->regs from ksz8795.c to the ksz_common.c. And
the regs is dereferrenced using dev->info->regs.

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