[SCSI] libsas: make ATA functions selectable by a config option

Not everyone wants libsas automatically to pull in libata.  This patch
makes the behaviour configurable, so you can build libsas with or
without ATA support.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/libsas/Kconfig

@@ -30,6 +30,13 @@ config SCSI_SAS_LIBSAS
 	  This provides transport specific helpers for SAS drivers which
 	  use the domain device construct (like the aic94xxx).
 
+config SCSI_SAS_ATA
+	bool "ATA support for libsas (requires libata)"
+	depends on SCSI_SAS_LIBSAS && ATA
+	help
+		Builds in ATA support into libsas.  Will necessitate
+		the loading of libata along with libsas.
+
 config SCSI_SAS_LIBSAS_DEBUG
 	bool "Compile the SAS Domain Transport Attributes in debug mode"
 	default y

drivers/scsi/libsas/Makefile

@@ -33,5 +33,5 @@ libsas-y +=  sas_init.o     \
 		sas_dump.o     \
 		sas_discover.o \
 		sas_expander.o \
-		sas_scsi_host.o \
-		sas_ata.o
+		sas_scsi_host.o
+libsas-$(CONFIG_SCSI_SAS_ATA) +=	sas_ata.o