[SCSI] mvsas: add support for 94xx phy tuning and multiple revisions

Add 94xx phy tuning to aid manufacturing.
Add support for 94xx multiple revisions: A0, B0, C0, C1, C2.

Signed-off-by: Xiangliang Yu <yuxiangl@marvell.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>