USB: dwc3: gadget: Run time resume dwc3 device in dwc3_gadget_start()

There might be scenario where dwc3_msm platform device is runtime
suspended and is in low power mode by the time composite_probe
calls dwc3_gadget_start(). If device is in low power mode and SW does
register access, it could cause crash. Hence runtime resume the
platform device before accessing the register in dwc3_gadget_start().

CRs-Fixed: 487270
Change-Id: I53676ba42478a8e9fcad0ea7fb24d6c87a57ed1a
Signed-off-by: Vijayavardhan Vennapusa <vvreddy@codeaurora.org>