][next] selftests: nettest: fix spelling mistake: "potocol" -> "protocol"

There is a spelling mistake in an error messgae. Fix it.
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Acked-by: NShuah Khan <skhan@linuxfoundation.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

tools/testing/selftests/net/nettest.c

@@ -1627,7 +1627,7 @@ int main(int argc, char *argv[])
 				args.protocol = pe->p_proto;
 			} else {
 				if (str_to_uint(optarg, 0, 0xffff, &tmp) != 0) {
-					fprintf(stderr, "Invalid potocol\n");
+					fprintf(stderr, "Invalid protocol\n");
 					return 1;
 				}
 				args.protocol = tmp;