[SCSI] libsas: fix build dependencies on libata

If you have the libsas with ATA support, it needs libata to function.
The problem is that if you compile in libsas, you can't build libata
as a module (however, vice versa you can).
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/libsas/Kconfig

@@ -32,7 +32,8 @@ config SCSI_SAS_LIBSAS
 
 config SCSI_SAS_ATA
 	bool "ATA support for libsas (requires libata)"
-	depends on SCSI_SAS_LIBSAS && ATA
+	depends on SCSI_SAS_LIBSAS
+	depends on ATA = y || ATA = SCSI_SAS_LIBSAS
 	help
 		Builds in ATA support into libsas.  Will necessitate
 		the loading of libata along with libsas.