net: dsa: microchip: move remaining register offset to ksz_chip_reg

This patch moves the broadcast ctrl, multicast ctrl and start control
registers from ksz_chip_dat to ksz_chip_reg.

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