[][kernel][mt7986][switch][Fix the issue of get phy_mode failed]

[Description]
Fix the issue of get phy_mode failed.

[Release-log]
N/A


Change-Id: I6f4d00b20c9290b48a8d68b1a833d6ec7995d466
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6766218
1 file changed