sim-config: Improve alive check after reset

BugzID: 56371

recipes-connectivity/sim-config/files/sim-config.py

@@ -27,14 +27,12 @@ def reset_modem():
     write_to_file(GPIO_PATH + 'gpio' + GPIO_SIM_RST + '/value', '1')
     time.sleep(2)
     write_to_file(GPIO_PATH + 'gpio' + GPIO_SIM_RST + '/value', '0')
-    print("reset done")
-    # Wait until modem rebooted   
-    while True:                  
-        dirs = os.listdir("/dev")                      
-        for file in dirs:        
-            if file == 'ttyACM2':
-                sys.exit(0);
+    # Wait until modem rebooted
+    while os.path.exists('dev/ttyACM0'):
         time.sleep(1)
+    while not os.path.exists('/dev/ttyACM0'):
+        time.sleep(1)
+    print("reset done")
 
 def is_rst_required():
     global rst