usb: gadget: pxa25x_udc: Constify static struct pxa25x_ep_ops

usb: gadget: pxa25x_udc: Constify static struct pxa25x_ep_ops

The struct pxa25x_ep_ops is only assigned to the ops field in the
usb_ep struct, which is a pointer to const struct usb_ep_ops.
Make it const to allow the compiler to put it in read-only memory.

Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Link: https://lore.kernel.org/r/20210728092052.4178-1-rikard.falkeborn@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>