net: sh_eth: Remove sh_eth_reset() from halt function

sh_eth_reset is function to reset Ether IP.
The MAC address is stored in IP, but it is initialized by this function.
OS (e.g. Linux Kernel) can not use this device when initialized.
This revises this problem.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu.nobuhiro@renesas.com>