Bluetooth: Delete an unnecessary check before the function call "kfree_skb"

The kfree_skb() function tests whether its argument is NULL and then
returns immediately. Thus the test around the call is not needed.

This issue was detected by using the Coccinelle software.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

net/bluetooth/cmtp/core.c

@@ -178,8 +178,7 @@ static inline int cmtp_recv_frame(struct cmtp_session *session, struct sk_buff *
 			cmtp_add_msgpart(session, id, skb->data + hdrlen, len);
 			break;
 		default:
-			if (session->reassembly[id] != NULL)
-				kfree_skb(session->reassembly[id]);
+			kfree_skb(session->reassembly[id]);
 			session->reassembly[id] = NULL;
 			break;
 		}