transport: Move printing of reader number/name to generic code

Let's avoid copy+pasting print statements everywhere.  The instances
do already have a __str__ method for the purpose of printing their name in a
generic way.

Change-Id: I663a9ea69bf7e7aaa6502896b6a71ef692f8d844
diff --git a/pySim/transport/modem_atcmd.py b/pySim/transport/modem_atcmd.py
index 9a4f0a5..88e6253 100644
--- a/pySim/transport/modem_atcmd.py
+++ b/pySim/transport/modem_atcmd.py
@@ -21,7 +21,6 @@
 import time
 import re
 import argparse
-import os
 from typing import Optional
 
 from pySim.utils import Hexstr, ResTuple
@@ -34,16 +33,13 @@
 
 class ModemATCommandLink(LinkBase):
     """Transport Link for 3GPP TS 27.007 compliant modems."""
+    name = "modem for Generic SIM Access (3GPP TS 27.007)"
 
     def __init__(self, opts: argparse.Namespace = argparse.Namespace(modem_dev='/dev/ttyUSB0',
                                                                      modem_baud=115200), **kwargs):
         device = opts.modem_dev
         baudrate = opts.modem_baud
         super().__init__(**kwargs)
-        if os.environ.get('PYSIM_INTEGRATION_TEST') == "1":
-            print("Using modem for Generic SIM Access (3GPP TS 27.007)")
-        else:
-            print("Using modem for Generic SIM Access (3GPP TS 27.007) at port %s" % device)
         self._sl = serial.Serial(device, baudrate, timeout=5)
         self._echo = False		# this will be auto-detected by _check_echo()
         self._device = device