Bluetooth: Convert L2CAP ident spinlock into a mutex

The spinlock protecting the L2CAP ident number can be converted into
a mutex since the whole processing is run in a workqueue. So instead
of using a spinlock, just use a mutex here.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index d8e7b93..1fffd92 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -625,11 +625,10 @@
 
 	struct delayed_work	info_timer;
 
-	spinlock_t		lock;
-
 	struct sk_buff		*rx_skb;
 	__u32			rx_len;
 	__u8			tx_ident;
+	struct mutex		ident_lock;
 
 	struct sk_buff_head	pending_rx;
 	struct work_struct	pending_rx_work;