LED support for QCA9980

[Nathaniel Filardo]

Hallo ath10k@,

It seems that LED support is still missing in the latest versions of
the Linux ath10k driver; if that's not so, please ignore this message
entirely. :)

Thanks to some hero's sleuthing around a GPL source dump
(https://forum.openwrt.org/viewtopic.php?pid=336237#p336237) and a
later suggestion to try flipping bits from userspace (using
https://github.com/billfarrow/pcimem), I can report that, at least for
the two QCA9980s in my possession (within the TP-Link C2600 gateway I
have) that the speculation is correct: kicking on bit 17 (the value of
ATH_BEELINER_LED) in 0x85018 of resource0 makes bit 17 in 0x85000 an
active-low controller for the LEDs attached to the chip.

I'd attempt to wire this knowledge into the ath10k driver and the
broader LED framework within Linux and submit a patch, but I have no
idea where to begin such a task.  Perhaps it is, nevertheless, useful
to know and have confirmed?  I know blinking LEDs are a low priority
relative to getting packets on and off the air. :)

Cheers,
--nwf;

P.S. Please CC as I am not subscribed to ath10k at .