[media] v4l2: add RF gain control

Add new RF tuner gain control named RF Gain. That is aimed for first
amplifier chip right after antenna connector.
There is existing LNA Gain control, which is quite same, but it is
aimed for cases amplifier is integrated to tuner chip. Some designs
have both, as almost all recent tuner silicons has integrated LNA/RF
amplifier in any case.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/v4l2-core/v4l2-ctrls.c

@@ -888,6 +888,7 @@ const char *v4l2_ctrl_get_name(u32 id)
 	case V4L2_CID_TUNE_DEEMPHASIS:		return "De-Emphasis";
 	case V4L2_CID_RDS_RECEPTION:		return "RDS Reception";
 	case V4L2_CID_RF_TUNER_CLASS:		return "RF Tuner Controls";
+	case V4L2_CID_RF_TUNER_RF_GAIN:		return "RF Gain";
 	case V4L2_CID_RF_TUNER_LNA_GAIN_AUTO:	return "LNA Gain, Auto";
 	case V4L2_CID_RF_TUNER_LNA_GAIN:	return "LNA Gain";
 	case V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO:	return "Mixer Gain, Auto";
@@ -1161,6 +1162,7 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type,
 	case V4L2_CID_PILOT_TONE_FREQUENCY:
 	case V4L2_CID_TUNE_POWER_LEVEL:
 	case V4L2_CID_TUNE_ANTENNA_CAPACITOR:
+	case V4L2_CID_RF_TUNER_RF_GAIN:
 	case V4L2_CID_RF_TUNER_LNA_GAIN:
 	case V4L2_CID_RF_TUNER_MIXER_GAIN:
 	case V4L2_CID_RF_TUNER_IF_GAIN:

include/uapi/linux/v4l2-controls.h

@@ -936,6 +936,7 @@ enum v4l2_deemphasis {
 
 #define V4L2_CID_RF_TUNER_BANDWIDTH_AUTO	(V4L2_CID_RF_TUNER_CLASS_BASE + 11)
 #define V4L2_CID_RF_TUNER_BANDWIDTH		(V4L2_CID_RF_TUNER_CLASS_BASE + 12)
+#define V4L2_CID_RF_TUNER_RF_GAIN		(V4L2_CID_RF_TUNER_CLASS_BASE + 32)
 #define V4L2_CID_RF_TUNER_LNA_GAIN_AUTO		(V4L2_CID_RF_TUNER_CLASS_BASE + 41)
 #define V4L2_CID_RF_TUNER_LNA_GAIN		(V4L2_CID_RF_TUNER_CLASS_BASE + 42)
 #define V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO	(V4L2_CID_RF_TUNER_CLASS_BASE + 51)