usb: dwc3: gadget: add a 'restore' argument to set_ep_config

That argument will be used in later patches when we
have working hibernation support. For now, always
pass it as false.

The idea of this patch is to decrease to size of
following patches and slowly add hibernation building
blocks to the gadget side of dwc3 so that it becomes
very easy to review the actual hibernation code.

[ balbi@ti.com : rewrote patch on top of current
	tree. Added commit log. ]

Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>