NSA/SKYRAD/C1 - IRT incorrect min/max value

The values of valid_min and valid_max for field sky_ir_temp were incorrectly assigned to 
-49.7 and +50.0 C, respectively. The actual values should be -60 and +40 C.

• Sky Infra-Red Temperature(sky_ir_temp)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Sky Infra-Red Temperature Minima(sky_ir_temp_min)