samples/bpf: adjust rlimit RLIMIT_MEMLOCK for xdp1

Default rlimit RLIMIT_MEMLOCK is 64KB, causes bpf map failure.
e.g.
[root@lab bpf]#./xdp1 -N $(</sys/class/net/eth2/ifindex)
failed to create a map: 1 Operation not permitted

Fix it.

Signed-off-by: Tushar Dave <tushar.n.dave@oracle.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>