samples: bpf: ensure that we don't load over MAX_PROGS programs

I can't see that we check prog_cnt to ensure it doesn't go over
MAX_PROGS.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

samples/bpf/bpf_load.c

@@ -107,6 +107,9 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
 		return -1;
 	}
 
+	if (prog_cnt == MAX_PROGS)
+		return -1;
+
 	fd = bpf_load_program(prog_type, prog, insns_cnt, license, kern_version,
 			      bpf_log_buf, BPF_LOG_BUF_SIZE);
 	if (fd < 0) {