hwmon: (fschmd) Fix check on unsigned in watchdog_write()

If unsigned the watchdog_trigger() return value will not be
checked correctly.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

drivers/hwmon/fschmd.c

@@ -819,7 +819,7 @@ static int watchdog_release(struct inode *inode, struct file *filp)
 static ssize_t watchdog_write(struct file *filp, const char __user *buf,
 	size_t count, loff_t *offset)
 {
-	size_t ret;
+	int ret;
 	struct fschmd_data *data = filp->private_data;
 
 	if (count) {