selinux: remove unnecessary pointer reassignment

(cherry pick from commit 83d4a806)

Commit f01e1af4 ("selinux: don't pass in NULL avd to avc_has_perm_noaudit")
made this pointer reassignment unnecessary. Avd should continue to reference
the stack-based copy.

Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: tweaked subject line]
Signed-off-by: Paul Moore <pmoore@redhat.com>
Bug: 22846070
Change-Id: Ie33688d163870705272607309a27fb7c8f870748