[WATCHDOG] struct file_operations should be const

Fix following warnings:
WARNING: struct file_operations should normally be const

Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

diff --git a/drivers/watchdog/rc32434_wdt.c b/drivers/watchdog/rc32434_wdt.c
index 071ff7bb..f6cccc9 100644
--- a/drivers/watchdog/rc32434_wdt.c
+++ b/drivers/watchdog/rc32434_wdt.c
@@ -247,7 +247,7 @@
 	return 0;
 }
 
-static struct file_operations rc32434_wdt_fops = {
+static const struct file_operations rc32434_wdt_fops = {
 	.owner		= THIS_MODULE,
 	.llseek		= no_llseek,
 	.write		= rc32434_wdt_write,