sysctl rc script is running twice on boot breaking carp.allow

sysctl rc script is running twice on boot which is causing the `net.inet.carp.allow` sysctl to be set back to 0 after the `ix-haready` rc script is setting it.

The 2nd calling of `sysctl` is happening by the `securelevel` rc script so just make sure `ix-haready` is called after `securelevel`.