pch_gbe: Fix the MAC Address load issue.

With the specification of hardware,
the processing at the time of driver starting was modified.

This device write automatically the MAC address read from serial ROM
into a MAC Adress1A/1B register at the time of power on reset.
However, when stable clock is not supplied,
the writing of MAC Adress1A/1B register may not be completed.
In this case, it is necessary to load MAC address to MAC Address1A/1B register
by the MAC Address1 load register.

This patch always does the above processing,
in order not to be dependent on system environment.

Signed-off-by: Toshiharu Okada <toshiharu-linux@dsn.okisemi.com>
Signed-off-by: David S. Miller <davem@davemloft.net>