[ALSA] oxygen: use an array of snd_kcontrol pointers

Use an array for the pointers to known controls so that it is easier to
add more.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
diff --git a/sound/pci/oxygen/oxygen_lib.c b/sound/pci/oxygen/oxygen_lib.c
index 9cd4be2..5b77c94 100644
--- a/sound/pci/oxygen/oxygen_lib.c
+++ b/sound/pci/oxygen/oxygen_lib.c
@@ -114,7 +114,7 @@
 		}
 	}
 
-	if (chip->spdif_input_bits_ctl) {
+	if (chip->controls[CONTROL_SPDIF_INPUT_BITS]) {
 		spin_lock_irq(&chip->reg_lock);
 		chip->interrupt_mask |= OXYGEN_INT_SPDIF_IN_CHANGE;
 		oxygen_write16(chip, OXYGEN_INTERRUPT_MASK,
@@ -122,7 +122,7 @@
 		spin_unlock_irq(&chip->reg_lock);
 
 		snd_ctl_notify(chip->card, SNDRV_CTL_EVENT_MASK_VALUE,
-			       &chip->spdif_input_bits_ctl->id);
+			       &chip->controls[CONTROL_SPDIF_INPUT_BITS]->id);
 	}
 }