Remove unnecessary use of String.valueOf() from GPSExtractor (commons-app#2958)

valueOf() was being used in cases where it wasn't necessary because the method is called implicitly; this patch removes these usages to make the code clearer and easier to read.

Author: Deskana

app/src/main/java/fr/free/nrw/commons/upload/GPSExtractor.java

@@ -122,7 +122,7 @@ private String getDecimalCoords(String latitude, String latitude_ref, String lon
             decLongitude = 0 - convertToDegree(longitude);
         }
 
-        String decimalCoords = String.valueOf(decLatitude) + "|" + String.valueOf(decLongitude);
+        String decimalCoords = decLatitude + "|" + decLongitude;
         Timber.d("Latitude and Longitude are %s", decimalCoords);
         return decimalCoords;
     }