docs: remove redundant return

[asashour]

This change is to remove redundant return doc, for a method with void type.

It prevents the success of opencv/opencv#14667, and the corresponding error is here

Please suggest if other text should be written instead.

opencv=javadoc
**WIP**
force_builders=Docs

[alalek]

Internal code comments must not be a part of public API documentation.

In other words - fixing .cpp can't help with documentation.
You should fix public .hpp file instead.