Patches intended for v5.4
* Remove (broken) d0i3 support;
* Debug infrastructure work continues;
* Bump support FW API version to 50;
* Fix for the SN value in certain suspend/resume situations;
* Some work on new FW scan APIs;
* Work on LTR FW APIs;
* New FW channel-switch support;
* Support new ACPI value for per-platform antenna gain;
* Support for single antenna diversity;
* Support for new WoWLAN FW API;
* Initial refactoring of the device selection code;
* A bunch of clean-ups;
* Other small fixes and improvements;