bsg: support for full generic block layer SG v3

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/block/Kconfig b/block/Kconfig
index 2859351..da12f26 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -51,4 +51,11 @@
 
 endif # BLOCK
 
+config BLK_DEV_BSG
+	bool "Block layer SG support"
+	default y
+	---help---
+	Saying Y here will enable generic SG (SCSI generic) v3
+	support for any block device.
+
 source block/Kconfig.iosched