gsm/gsm48.c: drop useless assignment

Change-Id: I96c1ba70e332199a4ca95e827a7562f953975af4
diff --git a/src/gsm/gsm48.c b/src/gsm/gsm48.c
index 1b25538..405c904 100644
--- a/src/gsm/gsm48.c
+++ b/src/gsm/gsm48.c
@@ -421,7 +421,6 @@
 	bcd[1] = val % 10;
 	val = val / 10;
 	bcd[0] = val % 10;
-	val = val / 10;
 }
 
 /*! \brief Checks is particular message is cipherable in A/Gb mode according to