Bug fixes: - Initialize variables before use. - Remove a KASSERT() that could falsely trigger if there are other sources   of NMIs in the system.
Bug fixes:
- Initialize variables before use.
- Remove a KASSERT() that could falsely trigger if there are other sources
  of NMIs in the system.

Efficiency tweak:
- When checking PMCs that overflowed, ignore PMCs that were not configured for
  sampling.

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