md/raid5: drop qd_idx from r6_state

We now have this value in stripe_head so we don't need to duplicate
it.

Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index 2934ee0..c2f37f2 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -239,7 +239,7 @@
 
 /* r6_state - extra state data only relevant to r6 */
 struct r6_state {
-	int p_failed, q_failed, qd_idx, failed_num[2];
+	int p_failed, q_failed, failed_num[2];
 };
 
 /* Flags */