phy: mt76x8-usb-phy: add slew rate calibration and remove non-mt7628 part

This patch adds slew rate calibration for mt76x8-usb-phy, removes code
which belongs to mt7620, and gets rid of using syscon and regmap by using
clock driver and reset controller.

Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
2 files changed