xstat: Add the residency RPC to the list of fs ops

Include the ResidencyRpc in the list of fs operation numbers that
can be display by xstat_cm_test.

Caught by coverity (#989029)

Reviewed-on: http://gerrit.openafs.org/9320
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
(cherry picked from commit 64630d07b893199431b601a73de23c303c61db40)

Change-Id: If14fb4e6929ea667b2dde18b381ab5c59c6bf8db
Reviewed-on: http://gerrit.openafs.org/11031
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>