Revert "[SCSI] Remove full sg table memset()"

A bit too eager - we definitely need to clear the sg table
initially, so that we don't accidentally have ->page & 0x01
true and think that is a chain pointer.

This reverts commit f5c0dde4c66421a3a2d7d6fa604a712c9b0744e5.
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 0c86be7..aac8a02 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -764,6 +764,8 @@
 		if (unlikely(!sgl))
 			goto enomem;
 
+		memset(sgl, 0, sizeof(*sgl) * sgp->size);
+
 		/*
 		 * first loop through, set initial index and return value
 		 */