Make wireshark happy.

Removing the P Bit from the fake LAPD frame will make wireshark
run the data through the GSM RSL dissector with the right SAPI
and LAPD preference setting.
diff --git a/src/misdn.c b/src/misdn.c
index 920349e..17d2669 100644
--- a/src/misdn.c
+++ b/src/misdn.c
@@ -141,7 +141,7 @@
 		.sapi		= addr->sapi & 0x3F,
 		.ea2		= 1,
 		.tei		= addr->tei & 0x7F,
-		.control_foo	= 0x13 /* UI with P set */,
+		.control_foo	= 0x03 /* UI */,
 	};	
 
 	struct pcaprec_hdr payload_header = {