hwmon: (adm9240) Fix writes into inX_max attributes

When converting the driver to use the devm_hwmon_device_register_with_info
API, the wrong register was selected when writing into inX_max attributes.
Fix it.

Fixes: 124b7e34

 ("hwmon: (adm9240) Convert to devm_hwmon_device_register_with_info API")
Reported-by: Chris Packham <Chris.Packham@alliedtelesis.co.nz>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>