sh_eth: no need to call ether_setup()

There's no need to call ether_setup() in the driver since prior alloc_etherdev()
call already arranges for it.

Suggested-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: David S. Miller <davem@davemloft.net>