Henotheistim commonly refers to belief in one god without denying the existence of others.
As explained with annotations HERE, Mormons are polytheistic and believe in countless gods.
The term henotheistic does not clarify, nor is it even applicable to, Mormonism.
The dictionary definitions seem a little off from the meaning ascribed by the creator of the word.
http://en.wikipedia.org/wiki/Henotheism