BG96 Test with NUCLEO_F429ZI

We only modified mbed_app.json as below and got a [Log.txt](https://github.com/ARMmbed/mbed-os-example-cellular/files/4243141/Log.txt).
Our Hardware connection is okay... but It looks like power of modem is not running.
For reference, This example(https://os.mbed.com/users/Daniel_Lee/code/mbed-os-example-cellular-BG96/) is running on our hardware setting.
Could you please check parameters and this log?

```
{
"config": {
"sock-type": "TCP",
"echo-server-hostname": {
"help": "Echo server host name.",
"value": "\"echo.mbedcloudtesting.com\""
},
"echo-server-port": {
"help": "Echo server port number.",
"value": 7
},
"trace-level": {
"help": "Options are TRACE_LEVEL_ERROR,TRACE_LEVEL_WARN,TRACE_LEVEL_INFO,TRACE_LEVEL_DEBUG",
"macro_name": "MBED_TRACE_MAX_LEVEL",
"value": "TRACE_LEVEL_INFO"
}
},
"target_overrides": {
"*": {
"target.network-default-interface-type": "CELLULAR",
"mbed-trace.enable": true,
"lwip.ipv4-enabled": false,
"ppp.ipv4-enabled": false,
"lwip.ipv6-enabled": true,
"ppp.ipv6-enabled": false,
"lwip.ethernet-enabled": false,
"lwip.ppp-enabled": false,
"lwip.tcp-enabled": true,
"platform.stdio-convert-newlines": true,
"platform.stdio-baud-rate": 115200,
"platform.default-serial-baud-rate": 115200,
"platform.stdio-buffered-serial": true,
"cellular.debug-at": true,
"cellular.use-apn-lookup": true,
"nsapi.default-cellular-sim-pin": "\"1234\"",
"nsapi.default-cellular-plmn": null,
"nsapi.default-cellular-apn": "\"lte-internet.sktelecom.com\"",
"nsapi.default-cellular-username": null,
"nsapi.default-cellular-password": null
},
"DISCO_L496AG": {
"target.macros_add": [
"CELLULAR_DEVICE=STModCellular"
],
"target.components_add": ["STMOD_CELLULAR"],
"stmod_cellular.provide-default": "true"
},
"NUCLEO_F429ZI": {
"QUECTEL_BG96.provide-default" : true,
"QUECTEL_BG96.rst" : "D9",
"QUECTEL_BG96.pwr" : "D7",
"QUECTEL_BG96.tx" : "D1",
"QUECTEL_BG96.rx" : "D0"
}
}
}
```

Start by reviewing mbed_app.json and the attached Log.txt, then compare the NUCLEO_F429ZI and QUECTEL_BG96 settings with the linked working BG96 example. Done means identifying the configuration or power-related discrepancy and documenting the required correction.

Written by the indexing model from the issue text.