esp_wifi: Fix some wifi bugs.

1. Send encrypted mgmt frames in pmf connection
2. Remove dependecy of SHA256 AKM on PMF
3. Fix null pointer dereference
4. Set TTLS default phase2 method as MSCHAPV2.

components/wpa_supplicant/src/crypto/tls_mbedtls.c

@@ -502,6 +502,10 @@ struct tls_connection * tls_connection_init(void *tls_ctx)
 
 void tls_connection_deinit(void *tls_ctx, struct tls_connection *conn)
 {
+	/* case: tls init failed */
+	if (!conn) {
+		return;
+	}
 	/* Free ssl ctx and data */
 	tls_mbedtls_conn_delete((tls_context_t *) conn->tls);
 	os_free(conn->tls);