nfp: add missing fall through statements

GCC 7 checks for fall through comments, add the two missing ones.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/nfp_net_common.c

@@ -1687,8 +1687,10 @@ static int nfp_net_rx(struct nfp_net_rx_ring *rx_ring, int budget)
 				continue;
 			default:
 				bpf_warn_invalid_xdp_action(act);
+				/* fall through */
 			case XDP_ABORTED:
 				trace_xdp_exception(dp->netdev, xdp_prog, act);
+				/* fall through */
 			case XDP_DROP:
 				nfp_net_rx_give_one(dp, rx_ring, rxbuf->frag,
 						    rxbuf->dma_addr);