samples: bpf: add xdp_sample_pkts to .gitignore

This commit adds xdp_sample_pkts to .gitignore which is
currently ommited from the ignore file.
Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

samples/bpf/.gitignore

@@ -44,5 +44,6 @@ xdp_redirect_cpu
 xdp_redirect_map
 xdp_router_ipv4
 xdp_rxq_info
+xdp_sample_pkts
 xdp_tx_iptunnel
 xdpsock