hwmon: (dell-smm-hwmon) Use a valid name attribute

As per Documentation/hwmon/sysfs-interface, hwmon name attributes must
not include '-', so replace 'dell-smm' with 'dell_smm'.

Fixes: 039ae58503f3 ("hwmon: Allow to compile dell-smm-hwmon driver without /proc/i8k")
Signed-off-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Acked-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/dell-smm-hwmon.c

@@ -777,7 +777,7 @@ static int __init i8k_init_hwmon(void)
 	if (err >= 0)
 		i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN2;
 
-	i8k_hwmon_dev = hwmon_device_register_with_groups(NULL, "dell-smm",
+	i8k_hwmon_dev = hwmon_device_register_with_groups(NULL, "dell_smm",
 							  NULL, i8k_groups);
 	if (IS_ERR(i8k_hwmon_dev)) {
 		err = PTR_ERR(i8k_hwmon_dev);