usb: dwc3: Notify super speed phy about link training

Notify super speed phy such as qmp phy to start/stop link
training (reset and connection done) so that phy can reset
training sequence buffer when required.

Change-Id: I6c1a07d5d4614d368d57e742569ec537e0212e51
Signed-off-by: Vamsi Krishna Samavedam <vskrishn@codeaurora.org>