V4L/DVB: dvb/dib8000: fix build warning

In file included from drivers/media/dvb/dvb-usb/dib0700_devices.c:14:
  drivers/media/dvb/frontends/dib8000.h: In function 'dib8000_get_adc_power':
  drivers/media/dvb/frontends/dib8000.h:112: warning: no return statement in function returning non-void

Fixed by adding a return to the dummy function.
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/frontends/dib8000.h

@@ -109,6 +109,7 @@ static inline void dib8000_pwm_agc_reset(struct dvb_frontend *fe)
 static inline s32 dib8000_get_adc_power(struct dvb_frontend *fe, u8 mode)
 {
 	printk(KERN_WARNING "%s: driver disabled by Kconfig\n", __func__);
+	return 0;
 }
 #endif