usb: dwc2: eliminate irq parameter from dwc2_gadget_init

The irq is available in hsotg already, so there's no need to pass it as
separate function parameter.

Signed-off-by: Vardan Mikayelyan <mvardan@synopsys.com>
Signed-off-by: Grigor Tovmasyan <tovmasya@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>