The IIOParamController and IIOMetadataController interfaces contain a single
'activate' method that currently returns 'void'. This provides no way to
distinguish whether the controller completed successfully or whether it
was cancelled by some user action. Instead, these methods should return
a boolean, and guarantee that the object they are controlling is left
untouched if 'false' is returned.

  This rfe is being filed as a result of public review feedback.

  The methods on IIOParam and IIOMetadata that call the 'activate' method
need to be changed to return boolean in order to allow them to propagate the
return value to the user.