hwmon: (dell-smm) Mark i8k_get_fan_nominal_speed as __init

Mark function i8k_get_fan_nominal_speed() as __init since
it is only used in code also marked as __init.

Signed-off-by: Armin Wolf <[e-mail]>
Reviewed-by: Pali Rohár <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Guenter Roeck <[e-mail]>

drivers/hwmon/dell-smm-hwmon.c

···
 /*
  * Read the fan nominal rpm for specific fan speed.
  */
-static int i8k_get_fan_nominal_speed(const struct dell_smm_data *data, int fan, int speed)
+static int __init i8k_get_fan_nominal_speed(const struct dell_smm_data *data, int fan, int speed)
 {
 	struct smm_regs regs = { .eax = I8K_SMM_GET_NOM_SPEED, };