HAL/serial followup

Marlin/src/HAL/AVR/HAL.h

   #if !WITHIN(SERIAL_PORT, -1, 3)
     #error "SERIAL_PORT must be from -1 to 3. Please update your configuration."
   #endif
-
   #define MYSERIAL0 customizedSerial1
 
   #ifdef SERIAL_PORT_2

Marlin/src/HAL/SAMD51/HAL.h

     #if SERIAL_PORT_2 == -1
       #define MYSERIAL1 Serial
     #elif WITHIN(SERIAL_PORT_2, 0, 3)
-      #define MYSERIAL0 MSERIAL(SERIAL_PORT_2)
+      #define MYSERIAL1 MSERIAL(SERIAL_PORT_2)
     #else
       #error "SERIAL_PORT_2 must be from -1 to 3. Please update your configuration."
     #endif

Marlin/src/HAL/STM32F1/HAL.h

   #endif
 #endif
 
-#ifdef DGUS_SERIAL
+#ifdef DGUS_SERIAL_PORT
   #if DGUS_SERIAL_PORT == 0
     #error "DGUS_SERIAL_PORT cannot be 0. (Port 0 does not exist.) Please update your configuration."
   #elif DGUS_SERIAL_PORT == SERIAL_PORT

Marlin/src/HAL/TEENSY40_41/HAL.h

   #if SERIAL_PORT_2 == -1
     #define MYSERIAL1 usbSerial
   #elif WITHIN(SERIAL_PORT_2, 0, 8)
-    #define MYSERIAL0 MSERIAL(SERIAL_PORT_2)
+    #define MYSERIAL1 MSERIAL(SERIAL_PORT_2)
   #else
       #error "SERIAL_PORT_2 must be from -1 to 8. Please update your configuration."
   #endif

Marlin/src/lcd/extui/lib/anycubic_i3mega/anycubic_i3mega_lcd.cpp

 AnycubicTFTClass::AnycubicTFTClass() {}
 
 void AnycubicTFTClass::OnSetup() {
-  ANYCUBIC_LCD_SERIAL.begin(115200);
+  #ifndef LCD_BAUDRATE
+    #define LCD_BAUDRATE 115200
+  #endif
+  LCD_SERIAL.begin(LCD_BAUDRATE);
+
   SENDLINE_DBG_PGM("J17", "TFT Serial Debug: Main board reset... J17"); // J17 Main board reset
   ExtUI::delay_ms(10);
 

Marlin/src/lcd/extui/malyan_lcd.cpp

      * it and translate into ExtUI operations where possible.
      */
     inbound_count = 0;
-    LCD_SERIAL.begin(500000);
+
+    #ifndef LCD_BAUDRATE
+      #define LCD_BAUDRATE 500000
+    #endif
+    LCD_SERIAL.begin(LCD_BAUDRATE);
 
     // Signal init
     write_to_lcd_P(PSTR("{SYS:STARTED}\r\n"));