Bluetooth: Do not use assignments in IF conditions

Fix checkpatch warnings concerning assignments in if conditions.
Signed-off-by: Szymon Janc <szymon.janc@tieto.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

net/bluetooth/cmtp/core.c

@@ -235,9 +235,12 @@ static void cmtp_process_transmit(struct cmtp_session *session)
 
 		size = min_t(uint, ((tail < 258) ? (tail - 2) : (tail - 3)), skb->len);
 
-		if ((scb->id < 0) && ((scb->id = cmtp_alloc_block_id(session)) < 0)) {
-			skb_queue_head(&session->transmit, skb);
-			break;
+		if (scb->id < 0) {
+			scb->id = cmtp_alloc_block_id(session);
+			if (scb->id < 0) {
+				skb_queue_head(&session->transmit, skb);
+				break;
+			}
 		}
 
 		if (size < 256) {