More clarification on how bus_dmamap_sync works.  Fix bogus text concerning bus_dmamem_alloc.
More clarification on how bus_dmamap_sync works.  Fix bogus text concerning
bus_dmamem_alloc.

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