SELinux: Fix /mnt/state/var/log/keepalived context

The default context mnt_t is incorrect. It should be var_log_t.

Bug: 1381770
Change-Id: I86a79ea1075ea2a6a567a78d628ab8a47f53ddd4
Merge "SELinux: Fix /mnt/state/var/log/keepalived context"