can: make struct proto const

can_ioctl is the only reason for struct proto to be non-const.
script/check-patch.pl suggests struct proto be const.

Setting the reference to the common can_ioctl() in all CAN protocols directly
removes the need to make the struct proto writable in af_can.c

Signed-off-by: Kurt Van Dijck <kurt.van.dijck@eia.be>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/can/bcm.c b/net/can/bcm.c
index 092dc88..871a0ad 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -1569,7 +1569,7 @@
 	return size;
 }
 
-static struct proto_ops bcm_ops __read_mostly = {
+static const struct proto_ops bcm_ops = {
 	.family        = PF_CAN,
 	.release       = bcm_release,
 	.bind          = sock_no_bind,
@@ -1578,7 +1578,7 @@
 	.accept        = sock_no_accept,
 	.getname       = sock_no_getname,
 	.poll          = datagram_poll,
-	.ioctl         = NULL,		/* use can_ioctl() from af_can.c */
+	.ioctl         = can_ioctl,	/* use can_ioctl() from af_can.c */
 	.listen        = sock_no_listen,
 	.shutdown      = sock_no_shutdown,
 	.setsockopt    = sock_no_setsockopt,