Brought back schedsofttty() (SMPng casualty).  Didn't bring back the other schedsoft*() functions since they have never been used.
Brought back schedsofttty() (SMPng casualty).  Didn't bring back the
other schedsoft*() functions since they have never been used.

Removed confused comment about not needing these functions.  The
functions delay scheduling of SWIs until the next hardclock tick.
For devices that only deliver a few characters per interrupt, this
reduces the number of calls to the scheduler by a large factor (about
115 for each sio port at 115200 bps).

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