thermal: tsens: Use Calibration offset data from QFPROM

Current code uses default calibration offset value. Switch
over to using Calibrated offset value read from the QFPROM
to calculate the slope and offset and compensate it with the
temperature read from TSENS.

Change-Id: Ifa839f284acb7d5bba07ff46d986eeebd2132dd2
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>