(experimental) enable open_eth for esp-idf

Author: softhack007

platformio.ini

@@ -1860,6 +1860,7 @@ build_flags = ${esp32_4MB_V4_M_base.build_flags}
   -DDEBUG -D WLED_DEBUG -DWLED_DEBUG_JSON ;; -DWLED_DEBUG_FS ;; max WLED debugging output
   -D WLED_USE_ETHERNET
   -D WLED_DISABLE_ESPNOW ;; ESP-NOW requires wifi, may crash with ethernet only
+  -D CONFIG_ETH_USE_OPENETH ;; enable open_eth support
   -D WLED_ETH_DEFAULT=2 ;; ESP32-POE board configuration (works with QEMU open_eth)
   ;; Static IP for QEMU testing - user-mode networking provides DHCP at 10.0.2.0/24
   ;; If DHCP fails, uncomment these lines to use static IP: