ALSA: oxygen: handle CD input configuration with a flag

There are more models without a CD input than with one, so handle this
explicitly with a device_config flag to avoid having to define a control
filter callback to filter it out.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/oxygen/oxygen.c b/sound/pci/oxygen/oxygen.c
index 289cb4d..f4fdf6d 100644
--- a/sound/pci/oxygen/oxygen.c
+++ b/sound/pci/oxygen/oxygen.c
@@ -505,7 +505,8 @@
 			 PLAYBACK_2_TO_AC97_1 |
 			 CAPTURE_0_FROM_I2S_1 |
 			 CAPTURE_1_FROM_SPDIF |
-			 CAPTURE_2_FROM_AC97_1,
+			 CAPTURE_2_FROM_AC97_1 |
+			 AC97_CD_INPUT,
 	.dac_channels = 8,
 	.dac_volume_min = 0,
 	.dac_volume_max = 255,