tools/bpf: fix test_sockmap failure

On one of our production test machine, when running
bpf selftest test_sockmap, I got the following error:
  # sudo ./test_sockmap
  libbpf: failed to create map (name: 'sock_map'): Operation not permitted
  libbpf: failed to load object 'test_sockmap_kern.o'
  libbpf: Can't get the 0th fd from program sk_skb1: only -1 instances
  ......
  load_bpf_file: (-1) Operation not permitted
  ERROR: (-1) load bpf failed

The error is due to not-big-enough rlimit
  struct rlimit r = {10 * 1024 * 1024, RLIM_INFINITY};

The test already includes "bpf_rlimit.h", which sets current
and max rlimit to RLIM_INFINITY. Let us just use it.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/test_sockmap.c

@@ -1413,18 +1413,12 @@ static int test_suite(void)
 
 int main(int argc, char **argv)
 {
-	struct rlimit r = {10 * 1024 * 1024, RLIM_INFINITY};
 	int iov_count = 1, length = 1024, rate = 1;
 	struct sockmap_options options = {0};
 	int opt, longindex, err, cg_fd = 0;
 	char *bpf_file = BPF_SOCKMAP_FILENAME;
 	int test = PING_PONG;
 
-	if (setrlimit(RLIMIT_MEMLOCK, &r)) {
-		perror("setrlimit(RLIMIT_MEMLOCK)");
-		return 1;
-	}
-
 	if (argc < 2)
 		return test_suite();