V4L/DVB (6794): Fix compilation when dib3000mc is compiled as a module

As reported by Andrew Morton:

> ERROR: "dibusb_dib3000mc_frontend_attach" [drivers/media/dvb/dvb-usb/dvb-usb-nova-t-usb2.ko] undefined!
> ERROR: "dibusb_dib3000mc_tuner_attach" [drivers/media/dvb/dvb-usb/dvb-usb-nova-t-usb2.ko] undefined!
> ERROR: "dibusb_dib3000mc_frontend_attach" [drivers/media/dvb/dvb-usb/dvb-usb-dibusb-mc.ko] undefined!
> ERROR: "dibusb_dib3000mc_tuner_attach" [drivers/media/dvb/dvb-usb/dvb-usb-dibusb-mc.ko] undefined!
> ERROR: "dibusb_dib3000mc_frontend_attach" [drivers/media/dvb/dvb-usb/dvb-usb-a800.ko] undefined!
> ERROR: "dibusb_dib3000mc_tuner_attach" [drivers/media/dvb/dvb-usb/dvb-usb-a800.ko] undefined
Signed-off-by: NMauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/dvb/dvb-usb/dibusb-common.c

@@ -223,7 +223,9 @@ static struct dibx000_agc_config dib3000p_panasonic_agc_config = {
 	.agc2_slope2 = 0x1e,
 };
 
-#ifdef CONFIG_DVB_DIB3000MC
+#if defined(CONFIG_DVB_DIB3000MC) || 					\
+	(defined(CONFIG_DVB_DIB3000MC_MODULE) && defined(MODULE))
+
 static struct dib3000mc_config mod3000p_dib3000p_config = {
 	&dib3000p_panasonic_agc_config,