misc: get_wwn_id_map() needs to return dict

If we can't find device ids, we need to return
a dict, not a list.

Signed-off-by: Sam Lang <sam.lang@inktank.com>

teuthology/misc.py

@@ -363,7 +363,7 @@ def get_wwn_id_map(remote, devs):
         stdout = r.stdout.getvalue()
     except:
         log.error('Failed to get wwn devices! Using /dev/sd* devices...')
-        return devs
+        return dict((d,d) for d in devs)
 
     devmap = {}