net: sh-eth: Remove bd_t from sh_eth_config()

bd_t is not used in sh_eth_config(). This deletes bd_t from sh_eth_config()

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>