During attach on some de(4) adapters the driver sends out a test packet as part of detecting the media.  Explicitly ensure that we don't send it to bpf(4) as bpf(4) isn't setup yet.  This worked by accident before the bpf interface stuff was reworked to avoid other races (bpf_peers_present, etc.) but now it needs an explicit check to avoid a panic.
During attach on some de(4) adapters the driver sends out a test packet as
part of detecting the media.  Explicitly ensure that we don't send it to
bpf(4) as bpf(4) isn't setup yet.  This worked by accident before the bpf
interface stuff was reworked to avoid other races (bpf_peers_present, etc.)
but now it needs an explicit check to avoid a panic.

MFC after:	3 days
PR:		kern/120915

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