megaraid_sas: add support for secure JBOD

This patch adds support for Secure Encrypting Drives (SED) in JBOD mode:

1) If the firmware supports SED JBOD, all non read/write commands to JBODs
   will be sent via firmware path, and read/write commands to JBODs will
   be sent via fastpath.
2) If the firmware does not support SED JBOD, driver will fall back to the
   old design, i.e. send all JBOD I/O via fastpath.

Signed-off-by: Sumit Saxena <sumit.saxena@avagotech.com>
Signed-off-by: Chaitra Basappa <chaitra.basappa@avagotech.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>