ath9k: owl-loader: fetch pci init values through nvmem

extends the owl loader to fetch important pci initialization
values - which are stored together with the calibration data -
through the nvmem subsystem.

This allows for much faster WIFI/ath9k initializations on devices
that do not require to perform any post-processing (like XOR'ing/
reversal or unpacking)... than the current way through the
firmware_request which involves the filesystem/userspace.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/bc79ba1c6f6435000577bf1e5f4d7ebe18a8df97.1630157099.git.chunkeey@gmail.com