Fixups for ESP32

Marlin/src/HAL/HAL_ESP32/HAL.h

 
 extern portMUX_TYPE spinlock;
 
-#define NUM_SERIAL 2
 #define MYSERIAL0 Serial
-#define MYSERIAL1 webSocketSerial
+
+#if ENABLED(WIFISUPPORT)
+  #define NUM_SERIAL 2
+  #define MYSERIAL1 webSocketSerial
+#else
+  #define NUM_SERIAL 1
+#endif
 
 #define CRITICAL_SECTION_START portENTER_CRITICAL(&spinlock)
 #define CRITICAL_SECTION_END   portEXIT_CRITICAL(&spinlock)

Marlin/src/HAL/HAL_ESP32/WebSocketSerial.cpp

 #if ENABLED(WIFISUPPORT)
 
 #include "WebSocketSerial.h"
-#include "wifi.h"
 
+extern WebSocketSerial webSocketSerial;
+
+#include "wifi.h"
 #include <AsyncTCP.h>
 #include <ESPAsyncWebServer.h>
 

Marlin/src/pins/pins_ESP32.h

  * Espressif ESP32 (Tensilica Xtensa LX6) pin assignments
  */
 
+#ifndef ARDUINO_ARCH_ESP32
+  "Oops! Select an ESP32 board in 'Tools > Board.'"
+#endif
+
 #define BOARD_NAME "Espressif ESP32"
 
 //
 #define X_STEP_PIN         128
 #define X_DIR_PIN          129
 #define X_ENABLE_PIN       130
-//#define X_CS_PIN            0
+//#define X_CS_PIN           0
 
 #define Y_STEP_PIN         131
 #define Y_DIR_PIN          132
 #define Y_ENABLE_PIN       133
-//#define Y_CS_PIN           13
+//#define Y_CS_PIN          13
 
 #define Z_STEP_PIN         134
 #define Z_DIR_PIN          135
 #define Z_ENABLE_PIN       136
-//#define Z_CS_PIN            5 // SS_PIN
+//#define Z_CS_PIN           5 // SS_PIN
 
 #define E0_STEP_PIN        137
 #define E0_DIR_PIN         138
 #define E0_ENABLE_PIN      139
-//#define E0_CS_PIN          21
+//#define E0_CS_PIN         21
 
 //
 // Temperature Sensors
 //
-#define TEMP_0_PIN         36   // Analog Input
-#define TEMP_BED_PIN       39   // Analog Input
+#define TEMP_0_PIN          36   // Analog Input
+#define TEMP_BED_PIN        39   // Analog Input
 
 //
 // Heaters / Fans
 //
-#define HEATER_0_PIN        2
-#define FAN_PIN            13
-#define HEATER_BED_PIN      4
+#define HEATER_0_PIN         2
+#define FAN_PIN             13
+#define HEATER_BED_PIN       4