mei: revamp me clients list handling

1. Use rw lock to access the me_clients list

2. Reuse already defined find functions also when
removing particular me client

3. Add wrappers for addition  and deletion

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 c8412d4..4f83e9aa 100644
--- a/drivers/misc/mei/hbm.c
+++ b/drivers/misc/mei/hbm.c
@@ -338,7 +338,8 @@
 	me_cl->client_id = res->me_addr;
 	me_cl->mei_flow_ctrl_creds = 0;
 
-	list_add(&me_cl->list, &dev->me_clients);
+	mei_me_cl_add(dev, me_cl);
+
 	return 0;
 }