Add comments to clarify why we need to run shutdown code on the BSP, update an old comment about boot() being MI, and note that splhigh() no longer disables interrupts.
Add comments to clarify why we need to run shutdown code on the BSP, update
an old comment about boot() being MI, and note that splhigh() no longer
disables interrupts.

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