check developer mode before calling SetStablePowerState

[ethan-tqa]

You need to check if the PC is in developer mode before calling SetStablePowerState. Otherwise the device will be removed, with the following error:

D3D12 ERROR: ID3D12Device::RemoveDevice: Device removal has been triggered for the following reason (DXGI_ERROR_INVALID_CALL: There is strong evidence that the application has performed an illegal or undefined operation, and such a condition could not be returned to the application cleanly through a return code). [ EXECUTION ERROR #232: DEVICE_REMOVAL_PROCESS_AT_FAULT] D3D12: SetStablePowerState is only available when developer mode is enabled.

http://stackoverflow.com/questions/41231586/how-to-detect-if-developer-mode-is-active-on-windows-10