selinux: cleanup the internal AVC counters on error in avc_update()

In AVC update we don't call avc_node_kill() when avc_xperms_populate()
fails, resulting in the avc->avc_cache.active_nodes counter having a
false value.In last patch this changes was missed , so correcting it.

Change-Id: Ic0298162cc766c0f21be7ab232e259766654dad3
Signed-off-by: Jaihind Yadav <jaihindyadav@codeaurora.org>
Signed-off-by: Ravi Kumar Siddojigari <rsiddoji@codeaurora.org>
Signed-off-by: vijay.rayabarapu <vijay.rayabarapu@codeaurora.org>