Fix -Wreorder warning

Author: pennam

src/tls/utility/Cert.h

@@ -147,12 +147,12 @@ class ArduinoIoTCloudCertClass {
     byte data[CERT_COMPRESSED_CERT_SLOT_LENGTH + CERT_SERIAL_NUMBER_LENGTH + CERT_AUTHORITY_KEY_ID_LENGTH];
   } _compressedCert;
 
-  /* only raw EC X Y values 64 byte */
-  const byte * _publicKey;
-
   byte * _certBuffer;
   int    _certBufferLen;
 
+  /* only raw EC X Y values 64 byte */
+  const byte * _publicKey;
+
   int versionLength();
   int issuerOrSubjectLength(const CertInfo& issuerOrSubjectData);
   int sequenceHeaderLength(int length);