samples: bpf: Remove unneeded semicolon

Eliminate the following coccicheck warning:
./samples/bpf/cookie_uid_helper_example.c:316:3-4: Unneeded semicolon
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1612322248-35398-1-git-send-email-yang.lee@linux.alibaba.com

samples/bpf/cookie_uid_helper_example.c

@@ -313,7 +313,7 @@ int main(int argc, char *argv[])
 			print_table();
 			printf("\n");
 			sleep(1);
-		};
+		}
 	} else if (cfg_test_cookie) {
 		udp_client();
 	}