usb: gadget: mv_udc_core: Remove unneeded condition

The removed condition is always true, since the endpoint descriptor is
set prior to calling the enable endpoint.

Signed-off-by: Ido Shayevitz <idos@codeaurora.org>
Acked-by: Yu Xu <yuxu@marvell.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>