hwmon: (tmp421) Remove duplicate return in switch-case

Use single read permission return in switch-case that handles
attributes in tmp421_is_visible().

Signed-off-by: Bruno Thomsen <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>

drivers/hwmon/tmp421.c

···
 	switch (attr) {
 	case hwmon_temp_fault:
 	case hwmon_temp_input:
-		return 0444;
 	case hwmon_temp_label:
 		return 0444;
 	case hwmon_temp_enable: