Change heating_status_counter to uint8_t

It has a max value of 14

Saves 28 bytes of flash and 1 byte of SRAM

Firmware/Marlin.h

@@ -324,7 +324,7 @@ extern unsigned long total_filament_used;
 void save_statistics(unsigned long _total_filament_used, unsigned long _total_print_time);
 extern uint8_t heating_status;
 extern unsigned int status_number;
-extern unsigned int heating_status_counter;
+extern uint8_t heating_status_counter;
 extern char snmm_filaments_used;
 extern unsigned long PingTime;
 extern bool no_response;

Firmware/Marlin_main.cpp

@@ -218,7 +218,7 @@ unsigned int status_number = 0;
 
 unsigned long total_filament_used;
 uint8_t heating_status;
-unsigned int heating_status_counter;
+uint8_t heating_status_counter;
 bool loading_flag = false;
 
 #define XY_NO_RESTORE_FLAG (mesh_bed_leveling_flag || homing_flag)

Firmware/ultralcd.cpp

@@ -583,7 +583,7 @@ void lcdui_print_status_line(void)
         lcd_set_cursor(7, 3);
         lcd_space(13);
 
-        for (unsigned int dots = 0; dots < heating_status_counter; dots++) {
+        for (uint8_t dots = 0; dots < heating_status_counter; dots++) {
             lcd_putc_at(7 + dots, 3, '.');
         }
         switch (heating_status) {