hwmon: Add sht4x Temperature and Humidity Sensor Driver

This patch adds a hwmon driver for the SHT4x Temperature and
Humidity sensor.

Signed-off-by: Navin Sankar Velliangiri <navin@linumiz.com>
[groeck: dropped unnecessary empty line and continuation lines]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>