temperature: Do not expose check_min/max_temp

Firmware/temperature.h

@@ -232,9 +232,6 @@ FORCE_INLINE void autotempShutdown(){
 
 void PID_autotune(float temp, int extruder, int ncycles);
 
-void check_min_temp();
-void check_max_temp();
-
 #ifdef FAN_SOFT_PWM
 extern unsigned char fanSpeedSoftPwm;
 #endif