dpaa2-eth: Add "fall through" comments

Add comments in the switch statement for XDP action to indicate
fallthrough is intended.
Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c

@@ -322,8 +322,10 @@ static u32 run_xdp(struct dpaa2_eth_priv *priv,
 		break;
 	default:
 		bpf_warn_invalid_xdp_action(xdp_act);
+		/* fall through */
 	case XDP_ABORTED:
 		trace_xdp_exception(priv->net_dev, xdp_prog, xdp_act);
+		/* fall through */
 	case XDP_DROP:
 		xdp_release_buf(priv, ch, addr);
 		ch->stats.xdp_drop++;