mei: add wrapper for queuing control commands.

Enclose the boiler plate code of allocating a control/hbm command cb
and enqueueing it onto ctrl_wr.list in a convenient wrapper
mei_cl_enqueue_ctrl_wr_cb().

This is a preparatory patch for enabling consecutive reads.

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/misc/mei/hbm.c b/drivers/misc/mei/hbm.c
index c8e8a8d..4b9495f 100644
--- a/drivers/misc/mei/hbm.c
+++ b/drivers/misc/mei/hbm.c
@@ -871,10 +871,10 @@
 		cl->state = MEI_FILE_DISCONNECTING;
 		cl->timer_count = 0;
 
-		cb = mei_io_cb_init(cl, MEI_FOP_DISCONNECT_RSP, NULL);
+		cb = mei_cl_enqueue_ctrl_wr_cb(cl, 0, MEI_FOP_DISCONNECT_RSP,
+					       NULL);
 		if (!cb)
 			return -ENOMEM;
-		list_add_tail(&cb->list, &dev->ctrl_wr_list.list);
 	}
 	return 0;
 }