Bluetooth: clean up error pointer checking

The bt_skb_sendmsg() function can't return NULL so there is no need to
check for that.  Several of these checks were removed previously but
this one was missed.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

include/net/bluetooth/bluetooth.h

@@ -494,7 +494,7 @@ static inline struct sk_buff *bt_skb_sendmmsg(struct sock *sk,
 	struct sk_buff *skb, **frag;
 
 	skb = bt_skb_sendmsg(sk, msg, len, mtu, headroom, tailroom);
-	if (IS_ERR_OR_NULL(skb))
+	if (IS_ERR(skb))
 		return skb;
 
 	len -= skb->len;