mISDN: comment out unused symbols

Fix this sparse warnings:

  drivers/isdn/hardware/mISDN/hfcmulti.c:794: warning: 'vpm_check' defined but not used
  drivers/isdn/mISDN/dsp_cmx.c:1546: warning: 'dsp_start_jiffies' defined but not used

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Acked-by: Karsten Keil <kkeil@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/isdn/mISDN/dsp_cmx.c b/drivers/isdn/mISDN/dsp_cmx.c
index e868c47..c884511 100644
--- a/drivers/isdn/mISDN/dsp_cmx.c
+++ b/drivers/isdn/mISDN/dsp_cmx.c
@@ -1543,7 +1543,9 @@
 static u32	samplecount;
 struct timer_list dsp_spl_tl;
 u32	dsp_spl_jiffies; /* calculate the next time to fire */
+#ifdef UNUSED
 static u32	dsp_start_jiffies; /* jiffies at the time, the calculation begins */
+#endif /* UNUSED */
 static struct timeval dsp_start_tv; /* time at start of calculation */
 
 void