[][kernel][mt7988][usb]Add USB 2.0 Phy preemphasis parameter support]

[Description]
Add USB 2.0 phy preemphasis parameter support

[Release-log]
N/A

Change-Id: I0543ec4c840706bafaf0727f6409f40cff5b8056
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/6378563
5 files changed