[media] Kconfig: add SDR support

Add software defined radio device support for media Kconfig.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
diff --git a/drivers/media/usb/Kconfig b/drivers/media/usb/Kconfig
index 39d824e..f8c1099 100644
--- a/drivers/media/usb/Kconfig
+++ b/drivers/media/usb/Kconfig
@@ -52,5 +52,9 @@
 source "drivers/media/usb/em28xx/Kconfig"
 endif
 
+if MEDIA_SDR_SUPPORT
+	comment "Software defined radio USB devices"
+endif
+
 endif #MEDIA_USB_SUPPORT
 endif #USB