Cleanup of detect return

src/drivers/px4io/px4io.cpp

@@ -1966,17 +1966,15 @@ detect(int argc, char *argv[])
 	if (g_dev == nullptr)
 		errx(1, "driver alloc failed");
 
-	if (OK != g_dev->detect()) {
+	ret = g_dev->detect()
+
 	delete g_dev;
 	g_dev = nullptr;
+
+	if (ret)
+		/* nonzero, error */
 		exit(1);
-	}
+	else
-
-	if (g_dev != nullptr) {
-		delete g_dev;
-		g_dev = nullptr;
-	}
-
 		exit(0);
 }