Fix off-by-one error: sc->twe_drive is an array of TWE_MAX_UNITS elements.
Fix off-by-one error: sc->twe_drive is an array of TWE_MAX_UNITS elements.

Reported by:	"Ted Unangst" <tedu@coverity.com>
Approved by:	rwatson (mentor)

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