usb: dwc3: Add support for POR upon composition switch

Composition switch to GSI transport based composition from
another GSI transport based composition requires power on
reset of USB controller to synchronize operation with USB
wrapper for GSI. Specifically GSI_EN bit cannot be
cleared without performing usb controller reset. Hence
introduce gadget restart operation to simulate vbus off
and vbus on and perform  this operation from gsi bind
config.

Change-Id: Ie4695807c73c2d14c0d9e17c486f34a90fd93ddb
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>