First batch of iwlwifi patches for 4.15 (v2)
* Cleanups: - remove an unused value that we read from the NVM;
- remove link quality measurement code that was never used;
* One FW command API update;
* A fix and an addition for PCI devices for the A000 family;
* Tiny refactor of ref/unref code used by runtime-PM;
* Some debugging improvements;
* Implementation of a more flexible way to define command queue sizes;
* ACPI code refactoring;
* Some coding-style fixes;
* Avoid redundant command to the firmware;
* Add a struct with the format of one FW command;
* Change an error log to a warning when the FW API is not aligned with
the driver (important during development);
* Change a WARN_ON to WARN_ONCE to make it more descriptive and less
noisy (i.e. no repeated warnings on a firmware triggered error);
* Dump PCI registers when an error occurs, to make it easier to debug;