mISDN: DSP now uses ring buffer for echo canceler

DSP now uses ring buffer for echo canceler.
Added missing include in l1oip_codec.c

Signed-off-by: Andreas Eversberg <andreas@eversberg.eu>
Signed-off-by: Karsten Keil <keil@b1-systems.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/isdn/mISDN/l1oip_codec.c b/drivers/isdn/mISDN/l1oip_codec.c
index e4ecba3..bbfd1b8 100644
--- a/drivers/isdn/mISDN/l1oip_codec.c
+++ b/drivers/isdn/mISDN/l1oip_codec.c
@@ -48,6 +48,7 @@
 
 #include <linux/vmalloc.h>
 #include <linux/mISDNif.h>
+#include <linux/in.h>
 #include "core.h"
 #include "l1oip.h"