usb: dwc3: gadget: make DWC3_EP_WEDGE do the right thing

This makes DWC3_EP_WEDGE do the right thing, which is
prevent DWC3_EP_WEDGE from ever being cleared by a
ClearFeature(HALT) command.

[ balbi@ti.com : allowed set_wedge to send SetHalt command
	to controller ]

Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>