LSM: SafeSetID: Stop releasing uninitialized ruleset

LSM: SafeSetID: Stop releasing uninitialized ruleset

BugLink: https://launchpad.net/bugs/1845391
The first time a rule set is configured for SafeSetID, we shouldn't be
trying to release the previously configured ruleset, since there isn't
one. Currently, the pointer that would point to a previously configured
ruleset is uninitialized on first rule set configuration, leading to a
crash when we try to call release_ruleset with that pointer.

Acked-by: Jann Horn <jannh@google.com>
Signed-off-by: Micah Morton <mortonm@chromium.org>
(cherry picked from commit 21ab8580b383f27b7f59b84ac1699cb26d6c3d69)
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Acked-by: John Johansen <john.johnansen@canonical.com>
Acked-by: Steve Beattie <steve.beattie@canonical.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>