[][kernel][common][eth][Update phylink_pcs support for the SGMII/USXGMII]

[Description]
Add phylink_resolve_flow() to the phylink_start().

If without this patch, MAC might loss flow control setting on the
fixed-link mode.

[Release-log]
N/A


Change-Id: I8a84d53716e96f3814e2afe99ed944f642c4fb73
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/7420931
1 file changed