[SCSI] mptsas: add SMP passthrough support via bsg

This patch adds support for SAS Management Protocol (SMP) passthrough
support via bsg.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Eric Moore <eric.moore@lsi.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>