[WATCHDOG] constify function pointer tables

"static struct file_operations" should be
"static const struct file_operations".

Signed-off-by: Jan Engelhardt <jengelh@computergmbh.de>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --git a/drivers/watchdog/ar7_wdt.c b/drivers/watchdog/ar7_wdt.c
index cdaab8c..2eb48c0 100644
--- a/drivers/watchdog/ar7_wdt.c
+++ b/drivers/watchdog/ar7_wdt.c
@@ -279,7 +279,7 @@
 	}
 }
 
-static struct file_operations ar7_wdt_fops = {
+static const struct file_operations ar7_wdt_fops = {
 	.owner		= THIS_MODULE,
 	.write		= ar7_wdt_write,
 	.ioctl		= ar7_wdt_ioctl,