Remove some long-dead cruft in the interrupt handling code which was never used in FreeBSD.
Remove some long-dead cruft in the interrupt handling code which was
never used in FreeBSD.

Approved by:	re

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