[ALSA] Add dummy obsoleted module options for backward compatibility

Added dummay obsoleted module options for backward compatibility
(to reduce possible bugzilla entries :)

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/atiixp.c b/sound/pci/atiixp.c
index 332a71d..14f912a 100644
--- a/sound/pci/atiixp.c
+++ b/sound/pci/atiixp.c
@@ -56,6 +56,10 @@
 module_param(spdif_aclink, bool, 0444);
 MODULE_PARM_DESC(spdif_aclink, "S/PDIF over AC-link.");
 
+/* just for backward compatibility */
+static int enable;
+module_param(enable, int, 0444);
+
 
 /*
  */