mpi3mr: 3rd Generation Tri-Mode NVMe/SAS/SATA MegaRaid / eHBA

This is Broadcom's mpi3mr driver for FreeBSD version 8.6.0.2.0.
The mpi3mr driver supports Broadcom SAS4116-based cards in the 9600
series: 9670W-16i, 9670-24i, 9660-16i, 9620-16i, 9600-24i, 9600-16i,
9600W-16e, 9600-16e, 9600-8i8e.

Initially only available as a module and on amd64/arm64, since that's
how it has been tested to date. Future commits will add it to the kernel
build and may expand the architectures it is supported on.

Co-authored-by: Chandrakanth Patil <chandrakanth.patil@broadcom.com>
Feedback-by: ken (prior versions)
Reviewed-by: imp
RelNotes: yes
Differential-Revision: https://reviews.freebsd.org/D36771
Differential-Revision: https://reviews.freebsd.org/D36772