usb: dwc3: Add support for GSI operations to gadget framework

Targets supporting h/w accelerated path over GSI require
GSI specific configuration of USB controller.

Add support to enable h/w accelerated path to IPA.
Include operations to configure USB endpoints as
GSI capable, allocate TRBs that are associated with
GSI capable endpoints, perform operations on these
endpoints, and enable the GSI wrapper in DWC3 controller.
This allows a function driver to use GSI based h/w
accelerated data path.

Change-Id: I62688c70a04b1fdab3e522e0af759ebab69d92d7
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>