Fix the following sparse warning:

drivers/hwmon/k10temp.c:189:12: warning: symbol 'k10temp_temp_label' was
not declared. Should it be static?
drivers/hwmon/k10temp.c:202:12: warning: symbol 'k10temp_in_label' was
not declared. Should it be static?
drivers/hwmon/k10temp.c:207:12: warning: symbol 'k10temp_curr_label' was
not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Link: https://lore.kernel.org/r/20200409084502.42126-1-yanaijie@huawei.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>