hwmon: qpnp-adc-voltage: Add temperature compensation

Add VBAT and OCV temperature compensation for PM8026v2.2.
The temperature compensation is required on top of
gain/offset calibration to compensate for variations
due to chip revision, manufacturer and temperature.

Change-Id: I7c62340a74a118d6f80e4e6bba51c2d07c4a57c6
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>