[SCSI] fix kconfig dependency warnings related to SCSI_SAS_ATTRS

Fix kconfig dependency warnings in scsi/Kconfig:

warning: (SCSI_SAS_LIBSAS && SCSI || SCSI_MPT2SAS && SCSI_LOWLEVEL && PCI && SCSI || FUSION_SAS && FUSION && PCI && SCSI) selects SCSI_SAS_ATTRS which has unmet direct dependencies (SCSI && BLK_DEV_BSG)

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>