isdn: mISDN, don't compile unused stuff

Remove these compiler warnings:

drivers/isdn/hardware/mISDN/w6692.c:534: warning: `setvolume' defined but not used
drivers/isdn/hardware/mISDN/w6692.c:561: warning: `enable_pots' defined but not used

by moving the functions inside #if 0 ...  #endif.  And an alternative is
to remove them completely if nobody has plans to use them.
Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
Cc: Karsten Keil <isdn@linux-pingi.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/isdn/hardware/mISDN/w6692.c

@@ -529,6 +529,7 @@ W6692_fill_Bfifo(struct w6692_ch *wch)
 	}
 }
 
+#if 0
 static int
 setvolume(struct w6692_ch *wch, int mic, struct sk_buff *skb)
 {
@@ -571,6 +572,7 @@ enable_pots(struct w6692_ch *wch)
 	WriteW6692(card, W_PCTL, card->pctl);
 	return 0;
 }
+#endif
 
 static int
 disable_pots(struct w6692_ch *wch)