Allow phy to be initialized only if WiFi/BLE is used/enabled

fixes: https://github.com/espressif/arduino-esp32/issues/72

cores/esp32/esp32-hal.h

@@ -65,6 +65,10 @@ uint32_t millis();
 void delay(uint32_t);
 void delayMicroseconds(uint32_t us);
 
+#if !CONFIG_ESP32_PHY_AUTO_INIT
+void arduino_phy_init();
+#endif
+
 #if !CONFIG_AUTOSTART_ARDUINO
 void initArduino();
 #endif