Introduce SENSOR_DEVICE_ATTR_{RO,RW,WO} and SENSOR_DEVICE_ATTR_2_{RO,RW,WO}
as simplified variants of SENSOR_DEVICE_ATTR and SENSOR_DEVICE_ATTR_2 to
simplify the source code, improve readbility, and reduce the chance of
inconsistencies.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>