Use uint16_t for temps

Marlin/temperature.cpp

 #endif
 
 #if WATCH_HOTENDS
-  int Temperature::watch_target_temp[HOTENDS] = { 0 };
+  uint16_t Temperature::watch_target_temp[HOTENDS] = { 0 };
   millis_t Temperature::watch_heater_next_ms[HOTENDS] = { 0 };
 #endif
 
 #if WATCH_THE_BED
-  int Temperature::watch_target_bed_temp = 0;
+  uint16_t Temperature::watch_target_bed_temp = 0;
   millis_t Temperature::watch_bed_next_ms = 0;
 #endif
 
 #if ENABLED(PREVENT_COLD_EXTRUSION)
   bool Temperature::allow_cold_extrude = false;
-  float Temperature::extrude_min_temp = EXTRUDE_MINTEMP;
+  uint16_t Temperature::extrude_min_temp = EXTRUDE_MINTEMP;
 #endif
 
 // private:
 
 #if ENABLED(TEMP_SENSOR_1_AS_REDUNDANT)
-  int Temperature::redundant_temperature_raw = 0;
+  uint16_t Temperature::redundant_temperature_raw = 0;
   float Temperature::redundant_temperature = 0.0;
 #endif
 

Marlin/temperature.h

     #endif
 
     #if WATCH_HOTENDS
-      static int watch_target_temp[HOTENDS];
+      static uint16_t watch_target_temp[HOTENDS];
       static millis_t watch_heater_next_ms[HOTENDS];
     #endif
 
     #if WATCH_THE_BED
-      static int watch_target_bed_temp;
+      static uint16_t watch_target_bed_temp;
       static millis_t watch_bed_next_ms;
     #endif
 
     #if ENABLED(PREVENT_COLD_EXTRUSION)
       static bool allow_cold_extrude;
-      static float extrude_min_temp;
+      static uint16_t extrude_min_temp;
       static bool tooColdToExtrude(uint8_t e) {
         #if HOTENDS == 1
           UNUSED(e);
   private:
 
     #if ENABLED(TEMP_SENSOR_1_AS_REDUNDANT)
-      static int redundant_temperature_raw;
+      static uint16_t redundant_temperature_raw;
       static float redundant_temperature;
     #endif