bpf: Reset data_meta before running programs attached to devmap entry

This is a new context that does not handle metadata at the moment, so
mark data_meta invalid.

Fixes: fbee97feed ("bpf: Add support to attach bpf program to a devmap entry")
Signed-off-by: David Ahern <dsahern@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200608151723.9539-1-dsahern@kernel.org

kernel/bpf/devmap.c

@@ -479,6 +479,7 @@ static struct xdp_buff *dev_map_run_prog(struct net_device *dev,
 	struct xdp_txq_info txq = { .dev = dev };
 	u32 act;
 
+	xdp_set_data_meta_invalid(xdp);
 	xdp->txq = &txq;
 
 	act = bpf_prog_run_xdp(xdp_prog, xdp);