net: ar8327: modify some configuration of switch

Imported from https://source.codeaurora.org/quic/qsdk/system/openwrt/commit/?h=korg/linux-3.4.y/release/arugula_bb_cs&id=2be4f8a8b205ae1a37db44839864451ebe893e6e


Signed-off-by: Pavel Kubelun <be.dissent@gmail.com>

Enable flow control of LAN and WAN ports to
get better performance.
Setup pvid as 0 for all ports during initialisation
to avoid confusion during system or switch INIT.
Disable PORT MAC before config MAC to avoid it work abnormal.
This change is for IR-054144, IR-057315.

Change-Id: I345f3dffa59ad3f97150e09692723da12a7b1067
Signed-off-by: Zou Shunxiang <shunxian@codeaurora.org>
Signed-off-by: xiaofeis <xiaofeis@codeaurora.org>