bgmac: Fix reversed test of build_skb() return value.

Fixes: f1640c3ddeec ("bgmac: fix a missing check for build_skb")
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bgmac.c

@@ -466,7 +466,7 @@ static int bgmac_dma_rx_read(struct bgmac *bgmac, struct bgmac_dma_ring *ring,
 			len -= ETH_FCS_LEN;
 
 			skb = build_skb(buf, BGMAC_RX_ALLOC_SIZE);
-			if (unlikely(skb)) {
+			if (unlikely(!skb)) {
 				bgmac_err(bgmac, "build_skb failed\n");
 				put_page(virt_to_head_page(buf));
 				break;