Remove static array of slots.  We now have state information for each slot in a softc for each unit that we probe.  Also remove validunits static, since it is no longer necessary.
Remove static array of slots.  We now have state information for each
slot in a softc for each unit that we probe.  Also remove validunits
static, since it is no longer necessary.

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