usb: remove useless declaration
usb: remove useless declaration

flexVDI/spice-gtk,SPICE/spice-gtk,SPICE/spice-gtk,Fantu/spice-gtk,fgouget/spice-gtk,SPICE/spice-gtk,flexVDI/spice-gtk,fgouget/spice-gtk,Fantu/spice-gtk,fgouget/spice-gtk,SPICE/spice-gtk,Fantu/spice-gtk,Fantu/spice-gtk