thermal: ti-soc-thermal: Fetch slope and offset from DT

Currently slope and offset values for calculating the hot spot
temperature of a thermal zone is being taken directly from driver
data. So fetch them from device tree.
Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

drivers/thermal/ti-soc-thermal/ti-thermal-common.c

@@ -96,8 +96,8 @@ static inline int __ti_thermal_get_temp(void *devdata, int *temp)
 		return ret;
 
 	/* Default constants */
-	slope = s->slope;
-	constant = s->constant;
+	slope = thermal_zone_get_slope(data->ti_thermal);
+	constant = thermal_zone_get_offset(data->ti_thermal);
 
 	pcb_tz = data->pcb_tz;
 	/* In case pcb zone is available, use the extrapolation rule with it */