pch_gbe: reprogram multicast address register on reset

The reset logic after a Rx FIFO overrun will clear the programmed
multicast addresses. This patch fixes the issue by reprogramming the
registers after the reset.

The commit eefc48b0

 ("pch_gbe: reprogram multicast address register on
reset") tried to fix this problem, but it introduces unnecessary
codes. In fact, all multicast addresses have been saved in netdev->mc,
So we can call pch_gbe_set_multi() directly after reset_hw and
reset_rx.

This commit kills 50+ line codes

Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Takahiro Shimizu <tshimizu818@gmail.com>
Signed-off-by: RongQing.Li <roy.qing.li@gmail.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>