[wifi] Reject EAP/WPA2 Enterprise config on unsupported platforms

WPA2 Enterprise (EAP) is only implemented for ESP32 and ESP8266 but the
config schema accepted it on all platforms. On RP2040 this caused a
bootloop with no useful error message. Now rejects EAP config at
validation time on unsupported platforms.

Closes https://github.com/esphome/esphome/issues/14743

esphome/components/wifi/__init__.py

@@ -166,6 +166,7 @@ TTLS_PHASE_2 = {
 }
 
 EAP_AUTH_SCHEMA = cv.All(
+    cv.only_on([Platform.ESP32, Platform.ESP8266]),
     cv.Schema(
         {
             cv.Optional(CONF_IDENTITY): cv.string_strict,