ANDROID: GKI: enable CONFIG_USB_DWC3 to be build in

Everyone relies on the DWC3 USB host/gadget controller, so build the
core into the kernel to be shared by all.

If platform specific changes are needed, enable the platform-specific
dwc3 driver.

Bug: 157965270
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I3fc2c4d05f46eebf30c2e222cb85928d9f6a83c5