libata: Fixup n_elem initialization

Fixup the inialization of qc->n_elem. It currently gets
initialized to 1 for commands that do not transfer any data.
Fix this by initializing n_elem to 0 and only setting to 1
in ata_scsi_qc_new when there is data to transfer. This fixes
some problems seen with SATA devices attached to ipr adapters.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/include/linux/libata.h b/include/linux/libata.h
index e53a13b..65d3187 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -1149,6 +1149,7 @@
 	qc->cursect = qc->cursg = qc->cursg_ofs = 0;
 	qc->nsect = 0;
 	qc->nbytes = qc->curbytes = 0;
+	qc->n_elem = 0;
 	qc->err_mask = 0;
 
 	ata_tf_init(qc->dev, &qc->tf);