[SCSI] mvsas: Add new macros and functions

Add new macros: MVS_SOFT_RESET, MVS_HARD_RESET, MVS_PHY_TUNE,
	MVS_COMMAND_ACTIVE, EXP_BRCT_CHG, MVS_MAX_SG
Add new member sg_width in struct mvs_chip_info
Use macros rather than magic number
Add new functions: mvs_fill_ssp_resp_iu, mvs_set_sense,
	mvs_94xx_clear_srs_irq, mvs_94xx_phy_set_link_rate

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