USB: Fix unneeded endpoint check in pxa27x_udc

The request allocation code doesn't need to check if the
endpoint is not NULL, as the only caller in
include/linux/usb/gadget.h, usb_ep_alloc_request() needs the
endpoint pointer to have a correct value to trigger the
allocation code.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>