BLE: CYW43XXX: set default baud rate on init()

Author: facchinm

connectivity/drivers/ble/FEATURE_BLE/COMPONENT_CYW43XXX/CyH4TransportDriver.cpp

@@ -127,6 +127,8 @@ void CyH4TransportDriver::initialize()
     bt_power = 0;
     rtos::ThisThread::sleep_for(1ms);
 
+    uart.baud(DEF_BT_BAUD_RATE);
+
     uart.format(
         /* bits */ 8,
         /* parity */ mbed::SerialBase::None,