thermal: tsens8974: Modify TSENS code to degC calculation

Modify the routine to instead use the integer division
calculation which is slightly better to check whether
the value needs to be rounded.

Change-Id: I29dfe7693755276caf53b1098a5e453f9085bb6b
Signed-off-by: Siddartha Mohanadoss <smohanad@codeaurora.org>