Input: mtk-pmic-keys - remove duplicated include from mtk-pmic-keys.c

iSOrt includes in alphabetical order and remove duplicated include file
linux/kernel.h

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>