Linux: Fixed argc check in sensors_main

Was checking for argc < 1, and should be argc < 2.

Signed-off-by: Mark Charlebois <charlebm@gmail.com>

src/modules/sensors/sensors_linux.cpp

@@ -2253,8 +2253,9 @@ Sensors::start()
 
 int sensors_main(int argc, char *argv[])
 {
-	if (argc < 1) {
-		errx(1, "usage: sensors {start|stop|status}");
+	if (argc < 2) {
+		warnx("usage: sensors {start|stop|status}");
+		return 0;
 	}
 
 	if (!strcmp(argv[1], "start")) {