media: firewire: Make structure fdtv_ca constant

Static structure fdtv_ca, of type dvb_device, is only used when it is
passed as the third argument to function dvb_register_device(). However,
in the definition of dvb_register_device, the third parameter is
declared as constant. Hence make fdtv_ca const as well.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/firewire/firedtv-ci.c

@@ -217,7 +217,7 @@ static const struct file_operations fdtv_ca_fops = {
 	.llseek		= noop_llseek,
 };
 
-static struct dvb_device fdtv_ca = {
+static const struct dvb_device fdtv_ca = {
 	.users		= 1,
 	.readers	= 1,
 	.writers	= 1,