qcacmn: Fix failing to drop m-pkts from the DUT itself

The DUT should drop the mcast packet from itself when
receiving it. However, a mcast packet from the DUT
itself has been failed to be discarded due to code
refactoring. This change aims at fixing this issue.

Change-Id: Ic80aa2aeb107b7b5a1b1d88f2ee0a72e316d7fcc
CRs-Fixed: 3372169

qdf/linux/src/qdf_nbuf.c

@@ -2535,13 +2535,15 @@ qdf_export_symbol(__qdf_nbuf_is_bcast_pkt);
 
 bool __qdf_nbuf_is_mcast_replay(qdf_nbuf_t nbuf)
 {
-	struct ethhdr *eh = (struct ethhdr *)qdf_nbuf_data(nbuf);
+	struct sk_buff *skb = (struct sk_buff *)nbuf;
+	struct ethhdr *eth = eth_hdr(skb);
+
+	if (qdf_likely(skb->pkt_type != PACKET_MULTICAST))
+		return false;
+
+	if (qdf_unlikely(ether_addr_equal(eth->h_source, skb->dev->dev_addr)))
+		return true;
 
-	if (unlikely(nbuf->pkt_type == PACKET_MULTICAST)) {
-		if (unlikely(ether_addr_equal(eh->h_source,
-					      nbuf->dev->dev_addr)))
-			return true;
-	}
 	return false;
 }