ath10k: support NET_DETECT WoWLAN feature

For WoWLAN support it is expected to support wake up based on discovery of
one or more known SSIDs. This is the WIPHY_WOWLAN_NET_DETECT feature,
which shows up as an NL80211 feature flag.

This shows up in 'iw phy' as:

WoWLAN support:
* wake up on network detection, up to 16 match sets

And it can be enabled with command:

iw phy0 wowlan enable net-detect interval 5000 delay 30 freqs 2412 matches ssid foo

Firmware will do scan by the configured parameters after suspend and
wakeup if it found matched SSIDs. Tested with QCA6174 hw3.0 with
firmware WLAN.RM.4.4.1-00110-QCARMSWPZ-1.

Signed-off-by: Wen Gong <wgong@codeaurora.org>
[kvalo@codeaurora.org: fix lots of endian bugs, whitespace, commit log and style cleanup]
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>