Merge pull request #8179 from kivaisan/add_default_cellular_sim_pin

Add missing SIM PIN configuration item

Author: Cruz Monrreal

features/netsocket/mbed_lib.json

@@ -6,6 +6,7 @@
         "default-wifi-ssid": null,
         "default-wifi-password": null,
         "default-wifi-security": "NONE",
+        "default-cellular-sim-pin": null,
         "default-cellular-apn": null,
         "default-cellular-username": null,
         "default-cellular-password": null,