Fix handling of uid and gid arguments during chown

It appears that the intended behavior of overlay chown was changed
in 00d8d42e9, but the argument handling was not updated to reflect
the removal of overlayKind. This led to a crash when only the
uid was specified, and a processing of the gid as the uid
otherwise.

Signed-off-by: Jonathon Anderson <janderson@ciq.co>

CHANGELOG.md

@@ -38,8 +38,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   to be changed accordingly
 - host overlays can globaly disbaled, but are enabled per default
 - `wwctl overlay build -H` will only build the overlays which are assigned to the nodes
-### Fixes
+### Fixed
 - GID is no longer changed to `0` when unspecified during chown
+- Proper handling of uid/gid arguments during `wwctl overlay chown`
 
 
 ## [4.1.0] - 2021-07-29