Compile error while using custom Lora radio in custom board.

Hi,

I am compiling the mbed lorawan example code using MBED CLI2. I have added a custom target board for STM3WB55RG. I have to use a custom Lora radio driver based on LR1110. I added the LR1110 driver in the folder mbed-os\connectivity\drivers\lora as a component like (SX1276) and created the CMake file. I also modified the custom_target file (to add LR1110 as component) using "components_add:" command. Also modified lora_radio_helper.h and CMake file at mbed-os\connectivity\drivers\lora folder. However, while compiling below error is generated. The same error is also generated when STM32WL is used as the component. STM32WL is defined in the mbed-os libraray and I didnot make any changes to it.

I have attached the CMake files which were modified and also the snaps of the lora_radio_helper.h and custom_target.json where modification were made.
[CMakeLists.txt](https://github.com/ARMmbed/mbed-tools/files/6088750/CMakeLists.txt)
[CMakeLists.txt](https://github.com/ARMmbed/mbed-tools/files/6088753/CMakeLists.txt)

Regards
Keerthi

Start by reproducing the mbed LoRaWAN example build with Mbed CLI2 and the custom STM32WB55RG target, using the attached compiler error as the starting point. Review the modified CMakeLists.txt files, custom_target.json, and lora_radio_helper.h, comparing the LR1110 and STM32WL component configuration with the existing SX1276 setup. Done means the example compiles successfully with the selected radio component.

Written by the indexing model from the issue text.