Fix carp(4) panics that can occur during carp interface configuration.
Fix carp(4) panics that can occur during carp interface configuration.

Approved by:	mlaier (mentor)
Reported by:	Scott Ullrich
MFC after:	1 week

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase