Add mrsas(4) driver from LSI official support of newer MegaRAID SAS
cards.  LSI has been maintaining this driver outside of the FreeBSD
tree.  It overlaps support of ThunderBolt and Invader cards that mfi(4)
supports.  By default mfi(4) will attach to cards.  If the tunable:
	hw.mfi.mrsas_enable=1
is set then mfi(4) will not probe and attach to these newer cards and
allow mrsas(4) to attach.  So by default this driver will not effect
a FreeBSD system unless mfi(4) is removed from the kernel or the
tunable is enabled.

mrsas(4) attaches disks to the CAM layer so it depends on CAM and devices
show up as /dev/daX.  mfiutil(8) does not work with mrsas.  The FreeBSD
version of MegaCli and StorCli from LSI do work with mrsas.  It appears
that StorCli only works with mrsas.  MegaCli appears to work with mfi(4)
and mrsas(4).

It would be good to add mfiutil(4) support to mrsas, emulations modes,
kernel logging, device aliases to ease the transition between mfi(4)
and mrsas(4).

Style issues should be resolved by LSI when they get committers approved.
The plan is get this driver in FreeBSD 9.3 to improve HW support.

Thanks to LSI for developing, testing and working with FreeBSD to
make this driver co-exist in FreeBSD.  This improves the overall
support of MegaRAID SAS.

Submitted by:	Kashyap Desai <Kashyap.Desai@lsi.com>
Reviewed by:	scottl
MFC after:	3 days
Sponsored by:	LSI