V4L/DVB (11251): tuner: prevent invalid initialization of t->config in set_type

Drivers that don't set "config" directly in the set_type function will
end up with an invalid configuration value. Check that the value is sane,
otherwise initialize to 0.

Thanks to James Edward Geiger & Steven Toth for reporting this bug.

Cc: Steven Toth <stoth@linuxtv.org>
Cc: James Edward Geiger <james.e.geiger@gmail.com>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/tuner-core.c

@@ -364,7 +364,8 @@ static void set_type(struct i2c_client *c, unsigned int type,
 	}
 
 	t->type = type;
-	t->config = new_config;
+	/* prevent invalid config values */
+	t->config = ((new_config >= 0) && (new_config < 256)) ? new_config : 0;
 	if (tuner_callback != NULL) {
 		tuner_dbg("defining GPIO callback\n");
 		t->fe.callback = tuner_callback;