Change custom_message_state_old and custom_message_state to uint8_t

I see max value as 7*7+10 = 59

Saves 100 byte of flash and 1 byte of SRAM

Firmware/Marlin_main.cpp

@@ -3118,7 +3118,7 @@ static void gcode_G80()
 #endif //PINDA_THERMISTOR
     // Save custom message state, set a new custom message state to display: Calibrating point 9.
     CustomMsg custom_message_type_old = custom_message_type;
-    unsigned int custom_message_state_old = custom_message_state;
+    uint8_t custom_message_state_old = custom_message_state;
     custom_message_type = CustomMsg::MeshBedLeveling;
     custom_message_state = (nMeasPoints * nMeasPoints) + 10;
     lcd_update(1);

Firmware/ultralcd.cpp

@@ -78,7 +78,7 @@ LcdCommands lcd_commands_type = LcdCommands::Idle;
 static uint8_t lcd_commands_step = 0;
 
 CustomMsg custom_message_type = CustomMsg::Status;
-unsigned int custom_message_state = 0;
+uint8_t custom_message_state = 0;
 
 
 bool isPrintPaused = false;

Firmware/ultralcd.h

@@ -121,7 +121,7 @@ enum class CustomMsg : uint_least8_t
 };
 
 extern CustomMsg custom_message_type;
-extern unsigned int custom_message_state;
+extern uint8_t custom_message_state;
 
 extern uint8_t farm_mode;
 extern int farm_timer;