[WATCHDOG] Documentation/watchdog/src/watchdog-simple.c: improve this code

#include <unistd.h>

#include <fcntl.h>

int main(int argc, const char *argv[]) {

int main(void)

{

	int fd = open("/dev/watchdog", O_WRONLY);

	int ret = 0;

	if (fd == -1) {

		perror("watchdog");

		exit(1);

		exit(EXIT_FAILURE);

	}

	while (1) {

		write(fd, "\0", 1);

		fsync(fd);

		ret = write(fd, "\0", 1);

		if (ret != 1) {

			ret = -1;

			break;

		}

		ret = fsync(fd);

		if (ret)

			break;

		sleep(10);

	}

	close(fd);

	return ret;

}