Wreorder: fix a variety of re-ordering warnings

Signed-off-by: Jon Trulson <jtrulson@ics.com>

src/hdxxvxta/hdxxvxta.hpp

@@ -141,11 +141,11 @@ namespace upm {
 
 
   protected:
+    mraa::Aio m_aioHum;
+
     // temperature is an optional feature of the humidity transmitter
     mraa::Aio *m_aioTemp;
 
-    mraa::Aio m_aioHum;
-
   private:
     float m_aref;
     int m_aResTemp;