Large I/Os on Promise controllers reported to cause UDMA ICRC errors and subsequent timeouts. Restore previous limit for now, at least until I will have hardware to experiment.
Large I/Os on Promise controllers reported to cause UDMA ICRC errors and
subsequent timeouts. Restore previous limit for now, at least until
I will have hardware to experiment.

PR:             kern/141438

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