sh_eth: enable wake-on-lan for sh7734

This is based on public datasheet for sh7734 which shows it has the
same behavior and registers for WoL as other versions of sh_eth.

Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: David S. Miller <davem@davemloft.net>