0 is not an invalid interrupt in the PCI world (just in the ia32 world), do not treat it as such.  This fixes the alpha boot problem.
0 is not an invalid interrupt in the PCI world (just in the ia32
world), do not treat it as such.  This fixes the alpha boot problem.

Reviewed by: drew, des

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