mISDN: fix sparse warning: symbol 'nskb' shadows an earlier one

Impact: define first occurence of variable 'nskb' in inner most possible scope

Fix this sparse warning:

  drivers/isdn/mISDN/dsp_core.c:746:20: warning: symbol 'nskb' shadows an earlier one
  drivers/isdn/mISDN/dsp_core.c:634:19: originally declared here
Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Acked-by: Karsten Keil <kkeil@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/mISDN/dsp_core.c

@@ -631,7 +631,6 @@ dsp_function(struct mISDNchannel *ch,  struct sk_buff *skb)
 	int			ret = 0;
 	u8			*digits;
 	int			cont;
-	struct			sk_buff *nskb;
 	u_long			flags;
 
 	hh = mISDN_HEAD_P(skb);
@@ -690,6 +689,7 @@ dsp_function(struct mISDNchannel *ch,  struct sk_buff *skb)
 			digits = dsp_dtmf_goertzel_decode(dsp, skb->data,
 				skb->len, (dsp_options&DSP_OPT_ULAW)?1:0);
 			while (*digits) {
+				struct sk_buff *nskb;
 				if (dsp_debug & DEBUG_DSP_DTMF)
 					printk(KERN_DEBUG "%s: digit"
 					    "(%c) to layer %s\n",