net: dsa: microchip: remove unused members in ksz_device

The name, regs_size and overrides members in struct ksz_device are
unused. Hence remove it.
And host_mask is used in only place of ksz8795.c file, which can be
replaced by dev->info->cpu_ports

Signed-off-by: Arun Ramadoss <arun.ramadoss@microchip.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>