[media] add documentation for struct dvb_tuner_info

Despite being used everywhere at DVB frontends, the
struct dvb_tuner_info were never documented.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Acked-by: Jonathan Corbet <corbet@lwn.net>

drivers/media/dvb-core/dvb_frontend.h

@@ -65,6 +65,20 @@ struct dvb_frontend_tune_settings {
 
 struct dvb_frontend;
 
+/**
+ * struct dvb_tuner_info - Frontend name and min/max ranges/bandwidths
+ *
+ * @name:		name of the Frontend
+ * @frequency_min:	minimal frequency supported
+ * @frequency_max:	maximum frequency supported
+ * @frequency_step:	frequency step
+ * @bandwidth_min:	minimal frontend bandwidth supported
+ * @bandwidth_max:	maximum frontend bandwidth supported
+ * @bandwidth_step:	frontend bandwidth step
+ *
+ * NOTE: frequency parameters are in Hz, for terrestrial/cable or kHz for
+ * satellite.
+ */
 struct dvb_tuner_info {
 	char name[128];