[ALSA] oxygen: generalize handling of DAC volume limits

Add fields for the DAC volume limits to the module structure so that
model drivers do not need to install their own control info handlers.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/oxygen/hifier.c

@@ -153,6 +153,8 @@ static const struct oxygen_model model_hifier = {
 		       PLAYBACK_1_TO_SPDIF |
 		       CAPTURE_0_FROM_I2S_1,
 	.dac_channels = 2,
+	.dac_volume_min = 0,
+	.dac_volume_max = 255,
 	.function_flags = OXYGEN_FUNCTION_SPI,
 	.dac_i2s_format = OXYGEN_I2S_FORMAT_LJUST,
 	.adc_i2s_format = OXYGEN_I2S_FORMAT_LJUST,