add the possibility to customize the delimiter of the ATHandler in ATCellularDevice class

Author: merge

connectivity/cellular/include/cellular/framework/AT/AT_CellularDevice.h

@@ -67,7 +67,7 @@ class AT_CellularDevice : public CellularDevice {
     };
 
 public:
-    AT_CellularDevice(FileHandle *fh);
+    AT_CellularDevice(FileHandle *fh, char* delim = "\r");
     virtual ~AT_CellularDevice();
 
     virtual nsapi_error_t clear();

connectivity/cellular/source/framework/AT/AT_CellularDevice.cpp

@@ -39,9 +39,9 @@ using namespace std::chrono_literals;
 #define DEFAULT_AT_TIMEOUT 1s // at default timeout
 const int MAX_SIM_RESPONSE_LENGTH = 16;
 
-AT_CellularDevice::AT_CellularDevice(FileHandle *fh) :
+AT_CellularDevice::AT_CellularDevice(FileHandle *fh, char* delim):
     CellularDevice(),
-    _at(fh, _queue, DEFAULT_AT_TIMEOUT, "\r"),
+    _at(fh, _queue, DEFAULT_AT_TIMEOUT, delim),
 #if MBED_CONF_CELLULAR_USE_SMS
     _sms(0),
 #endif // MBED_CONF_CELLULAR_USE_SMS