Replace CustomMsg::MsgUpdate with CustomMsg::M117

MsgUpdate was only used with M117, renaming the message type to M117 may be more descriptive for current use case.

Firmware/ultralcd.cpp

@@ -618,7 +618,7 @@ void lcdui_print_status_line(void)
         }
     } else { // Otherwise check for other special events
         switch (custom_message_type) {
-        case CustomMsg::MsgUpdate: //Short message even while printing from SD
+        case CustomMsg::M117:   // M117 Set the status line message on the LCD
         case CustomMsg::Status: // Nothing special, print status message normally
         case CustomMsg::M0Wait: // M0/M1 Wait command working even from SD
             lcd_print(lcd_status_message);
@@ -676,9 +676,6 @@ void lcdui_print_status_line(void)
         case CustomMsg::Resuming: //Resuming
             lcd_puts_at_P(0, 3, _T(MSG_RESUMING_PRINT));
             break;
-        case CustomMsg::M117:
-            lcd_print(lcd_status_message);
-            break;
         }
     }
 

Firmware/ultralcd.h

@@ -121,9 +121,8 @@ enum class CustomMsg : uint_least8_t
     TempCal,         //!< PINDA temperature calibration
     TempCompPreheat, //!< Temperature compensation preheat
     M0Wait,          //!< M0/M1 Wait command working even from SD
-    MsgUpdate,       //!< Short message even while printing from SD
+    M117,            //!< M117 Set the status line message on the LCD
     Resuming,        //!< Resuming message
-    M117,            //!< M117 Custom Message to be displayed
 };
 
 extern CustomMsg custom_message_type;