linux-phytec-fsl

hwmon: (ads7871) Convert to devm_hwmon_device_register_with_groups

Use ATTRIBUTE_GROUPS macro and devm_hwmon_device_register_with_groups() to
simplify the code a bit.

The update_lock mutex is not used, so remove it.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>