linux-v4l2: Hide modinfo from terminal

Using modinfo dumps all the output into the terminal instead redirect
all output to dev/null.

plugins/linux-v4l2/linux-v4l2.c

@@ -31,7 +31,7 @@ static bool v4l2loopback_installed()
 {
 	bool loaded = false;
 
-	int ret = system("modinfo v4l2loopback");
+	int ret = system("modinfo v4l2loopback &>/dev/null");
 
 	if (ret == 0)
 		loaded = true;