config: Add default values on conversion

When config is created during mixer init, default values are set for
all variables. To mimic this behavior, LoadDefaults must be called on
conversion as well.
There is also no need to perform a conversion if the parsed version
number is the same as the current version number.

Signed-off-by: Rodrigo Chiossi <rodrigo.chiossi@intel.com>

config/config.go

@@ -449,10 +449,22 @@ func (config *MixConfig) Convert(filename string) error {
 		return err
 	}
 
+	if err := config.LoadDefaults(false); err != nil {
+		return err
+	}
+
+	// Reset version for files without versioning
+	config.version = "0.0"
+
 	if err := config.Parse(); err != nil {
 		return err
 	}
 
+	// Config is already in the current format
+	if config.version == CurrentConfigVersion {
+		return nil
+	}
+
 	if err := helpers.CopyFile(config.filename+".bkp", config.filename); err != nil {
 		return err
 	}