[Darwin]: sensor_service POS_3V3_ALW missing compute attribute

[aalamsi22]

Description

This fixes an issue where the sensor POS_3V3_ALW was throwing critical alarms due to a missing configuration with how the sensor value is computed.

POS_3V3_ALW 3273.000000 2025-01-28 14:29:21.0 PST
3.795000 2.800000

The new added "compute": "@/1000.0" will correctly calculate the sensor value.

Testing

Value reported is within thresholds.