[ALSA] oxygen: make line-in exclusive only on Xonar

Move the line input switching code to the Virtuoso driver because only
the Xonar cards bypass the analog mixer for line input.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
diff --git a/sound/pci/oxygen/oxygen.h b/sound/pci/oxygen/oxygen.h
index 9ec9e6b..8fc9e7c 100644
--- a/sound/pci/oxygen/oxygen.h
+++ b/sound/pci/oxygen/oxygen.h
@@ -84,6 +84,8 @@
 			       struct snd_pcm_hw_params *params);
 	void (*update_dac_volume)(struct oxygen *chip);
 	void (*update_dac_mute)(struct oxygen *chip);
+	void (*ac97_switch_hook)(struct oxygen *chip,
+				 unsigned int reg, int mute);
 	size_t model_data_size;
 	u8 dac_channels;
 	u8 used_channels;