Cosmetic: don't unconditionally probe i2c-piix4 since that is no longer common to all our machines.
Cosmetic: don't unconditionally probe i2c-piix4 since that is no longer
common to all our machines.

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome