usb: gadget: ECM: Add support for ECM over DWC3 controller

ECM is a USB tethering interface that is using HW accelerated
path via BAM2BAM.

This change adds the required support to enable the BAM2BAM
path for ECM also on DWC3 new USB controller.

Change-Id: Iad12e534ae05a6ef46fabf89ce71601b7ea67ecf
Signed-off-by: Bar Weiner <bweiner@codeaurora.org>
Signed-off-by: Maya Erez <merez@codeaurora.org>