[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/via82xx_modem.c b/sound/pci/via82xx_modem.c
index a7a60d8..9462ebf 100644
--- a/sound/pci/via82xx_modem.c
+++ b/sound/pci/via82xx_modem.c
@@ -66,6 +66,10 @@
 module_param(ac97_clock, int, 0444);
 MODULE_PARM_DESC(ac97_clock, "AC'97 codec clock (default 48000Hz).");
 
+/* just for backward compatibility */
+static int enable;
+module_param(enable, int, 0444);
+
 
 /*
  *  Direct registers