nfc: pn533: Constify pn533_phy_ops

Neither the driver or the core modifies the pn533_phy_ops struct, so
make them const to allow the compiler to put the static structs in
read-only memory.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/nfc/pn533/usb.c b/drivers/nfc/pn533/usb.c
index bd7f747..6f71ac7 100644
--- a/drivers/nfc/pn533/usb.c
+++ b/drivers/nfc/pn533/usb.c
@@ -429,7 +429,7 @@ static void pn533_send_complete(struct urb *urb)
 	}
 }
 
-static struct pn533_phy_ops usb_phy_ops = {
+static const struct pn533_phy_ops usb_phy_ops = {
 	.send_frame = pn533_usb_send_frame,
 	.send_ack = pn533_usb_send_ack,
 	.abort_cmd = pn533_usb_abort_cmd,