No log bit in IOCStatus and endian-safe changes.

Use MPI2_IOCSTATUS_MASK when checking IOCStatus to mask off the log bit, and
make a few more things endian-safe.

Reviewed by: ken, scottl, ambrisko, asomers
Approved by: ken, scottl, ambrisko
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D6097