Treat min,max of 0,0 for IRQ special.  Reject it if we didn't specifically assing an IRQ.  Add better comments while I'm here.
Treat min,max of 0,0 for IRQ special.  Reject it if we didn't specifically
assing an IRQ.  Add better comments while I'm here.

MFC after: 1 day
# Note: That's merging all the -current pci pcic code, not just this one
# change for the Aug 15th code freeze.

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