[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>

drivers/watchdog/hpwdt.c

@@ -602,7 +602,7 @@ static long hpwdt_ioctl(struct file *file, unsigned int cmd,
 /*
  *	Kernel interfaces
  */
-static struct file_operations hpwdt_fops = {
+static const struct file_operations hpwdt_fops = {
 	.owner = THIS_MODULE,
 	.llseek = no_llseek,
 	.write = hpwdt_write,

drivers/watchdog/rc32434_wdt.c

@@ -247,7 +247,7 @@ static long rc32434_wdt_ioctl(struct file *file, unsigned int cmd,
 	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,