simutil: Made UMTS/GSM authenticate more consitent

The Le parameter in the AUTHENTICATE command was not being
set for GSM authentication. This did work, but explicitly
setting it to 0 as UMTS does was more consitent.

src/simutil.c

@@ -1628,9 +1628,10 @@ static int build_authenticate(unsigned char *buffer, const unsigned char *rand,
 		buffer[pos++] = 0x10;
 		memcpy(buffer + pos, autn, 16);
 		pos += 16;
-		buffer[pos++] = 0x00;
 	}
 
+	buffer[pos++] = 0x00;
+
 	return pos;
 }