netlink: specs: wireless: add a spec for nl80211

Add a rudimentary YNL spec for nl80211 that covers get-wiphy,
get-interface and get-protocol-features.

./tools/net/ynl/pyynl/cli.py --family nl80211 \
    --do get-protocol-features
{'protocol-features': {'split-wiphy-dump'}}

./tools/net/ynl/pyynl/cli.py --family nl80211 \
    --dump get-wiphy --json '{ "split-wiphy-dump": true }'

./tools/net/ynl/pyynl/cli.py --family nl80211 \
    --dump get-interface

Signed-off-by: Donald Hunter <[email protected]>
Acked-by: Johannes Berg <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: donaldh