applications: nrf5340_audio: Buildprog transport mandatory

OCT-3328
Now forces the -t/--transport option in buildprog as mandatory

Signed-off-by: Graham Wacey <graham.wacey@nordicsemi.no>

Author: gWacey

applications/nrf5340_audio/doc/building.rst

@@ -98,6 +98,10 @@ The building command for running the script requires providing the following par
      - ``release``, ``debug``
      - | :ref:`nrf53_audio_app_configuration_files`
        | **Note:** For FOTA DFU, you must use :ref:`nrf53_audio_app_building_standard`.
+   * - Transport type (``-t``)
+     - Specifies the transpoert type.
+     - ``broadcast``, ``unicast``
+     - :ref:`nrf53_audio_app_overview_broadcast_unicast`
    * - Device type (``-d``)
      - Specifies the device type.
      - ``headset``, ``gateway``, ``both``
@@ -107,7 +111,7 @@ For example, the following command builds headset and gateway applications using
 
 .. code-block:: console
 
-   python buildprog.py -c app -b debug -d both
+   python buildprog.py -c app -b debug -d both -t unicast
 
 The command can be run from any location, as long as the correct path to :file:`buildprog.py` is given.
 
@@ -132,9 +136,9 @@ The command for programming can look as follows:
 
 .. code-block:: console
 
-   python buildprog.py -c both -b debug -d both -p
+   python buildprog.py -c both -b debug -d both -t unicast -p
 
-This command builds the headset and the gateway applications with ``debug`` version of both the application core binary and the network core binary - and programs each to its respective core.
+This command builds the unicast headset and the gateway applications with ``debug`` version of both the application core binary and the network core binary - and programs each to its respective core.
 If you want to rebuild from scratch, you can add the ``--pristine`` parameter to the command (west's ``-p`` for cannot be used for a pristine build with the script).
 
 .. note::
@@ -143,7 +147,7 @@ If you want to rebuild from scratch, you can add the ``--pristine`` parameter to
 
    .. code-block:: console
 
-      python buildprog.py -c both -b debug -d both -p --recover_on_fail
+      python buildprog.py -c both -b debug -d both -t unicast -p --recover_on_fail
 
 Getting help
 ------------

applications/nrf5340_audio/tools/buildprog/buildprog.py

@@ -312,7 +312,7 @@ def __main():
     parser.add_argument(
         "-t",
         "--transport",
-        type=str,
+        required = True,
         choices=[i.name for i in Transport],
         default=Transport.unicast.name,
         help="Select the transport type",