Fix: rotation client example: leak of handle on error

Fix: rotation client example: leak of handle on error

1452927 Resource leak

The system resource will not be reclaimed and reused, reducing the
future availability of the resource.

In setup_session: Leak of memory or pointers to system
resources (CWE-404)

CID 1452927 (#1 of 1): Resource leak (RESOURCE_LEAK)8. leaked_storage:
Variable chan_handle going out of scope leaks the storage it points to

Reported-by: Coverity Scan
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I4c215ac4a86f9f70fd5c9d3aa13f944d3d7a2cc7