Add support for SAS3.5 megaraids, which are sold as Dell PERC H740P/840 and

Add support for SAS3.5 megaraids, which are sold as Dell PERC H740P/840 and
Lenovo ThinkSystem RAID 530/930.  The main differences are in fast path
IO, which we don't use, so all we have to deal with is some changes in the
raid context layout and different PCI BARs.  The mfii_iop structure gets
rearranged a bit to accommodate these.

tested on a perc h740p and a h730 (by dlg@)
ok dlg@