ath10k-ct: add Coverage Class setting ipq40xx and qca99xx WiFi (WIP)

ath10k-ct: add Coverage Class setting ipq40xx and qca99xx WiFi (WIP)

Since QCA wireless firmware version 10.4 the Coverage Class can be set
for ipq40xx and qca99xx circuits via the wmi interface.
A timeout value adjusts protocol timing for the extra radio propagation
time that is inherent to transmission over larger than local distances.

In due time an upstream patch in mac80211 can be anticipated.
This patch enables use of ipq40xx SoC based devices in OpenWrt in the
mean time when Coverage Class setting is required.

Authors:
Sebastian Gottschall    <s.gottschall@dd-wrt.com>
William Wortel          <wwortel@dorpstraat.com>

Signed-off-by: William Wortel <wwortel@dorpstraat.com>
Signed-off-by: Koen Vandeputte <koen.vandeputte@citymesh.com>