Fix reorder-init-list in power telemetry

```
stack_power_telemetry.cc:518:7: warning: ISO C++ requires field
designators to be specified in declaration order;
field 'channel_type' will be initialized after field 'src'
[-Wreorder-init-list]
      .src.cid = static_cast<uint16_t>(src_id),
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
stack_power_telemetry.cc:517:23: note: previous initialization for field
'channel_type' is here
      .channel_type = channel_type,
                      ^~~~~~~~~~~~
 ```

Bug: 297606425
Test: m Bluetooth | Only build needed no-op change
Change-Id: Ifad027799e58a93afb11ea97c54c30adefb104ea