Revert and remake r209883: Do not grab lock while setting up interrupt, as it causes LOR with allocation code. Instead make interrupt handler check that CAM bus initialization completed before touching it.
Revert and remake r209883:
Do not grab lock while setting up interrupt, as it causes LOR with
allocation code. Instead make interrupt handler check that CAM bus
initialization completed before touching it.

While there, slightly improve attach errors handling.

Reported by:	kib

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