net/sh-eth: Check return value of sh_eth_reset when chip reset fail

The sh_eth_reset function resets chip, but this performs nothing when failed.
This changes sh_eth_reset return an error, when this failed in reset.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Signed-off-by: David S. Miller <davem@davemloft.net>