usb: dwc3: omap: add multiple instances support to OMAP

if we ever have an omap with multiple instances of
the DWC3 IP, we need unique names for them. In order
to achieve that, let's use the dwc3_get/put_device_id()
calls to give us an unique device identifier.

Signed-off-by: Felipe Balbi <balbi@ti.com>