Revert "usb: dwc3: Notify super speed phy about link training"

This reverts commit 51ba5b1e.

The workaround is no longer required for current HW.

Change-Id: I0abd01846cbb9f15b5dbed6dff5ca6f19d40de30
Signed-off-by: Jack Pham <jackp@codeaurora.org>