nl80211: Allow privileged operations from user namespaces

While a wiphy can be transferred to network namespaces, a process having
CAP_NET_ADMIN in a non-initial user namespace can not administrate such
devices due to the genetlink GENL_ADMIN_PERM restrictions.

For openvswitch having the same issue, a new GENL_UNS_ADMIN_PERM flag has
been introduced, commit 4a92602a ("openvswitch: allow management from
inside user namespaces"). This patch changes all privileged operations
operating on a wiphy, dev or wdev to allow their administration using the
same mechanism. All operations use either NEED_WIPHY, NEED_WDEV or
NEED_NETDEV, which implies a namespace aware lookup of the device. The only
exception is NL80211_CMD_SET_WIPHY, which explicitly uses a namespace aware
phy lookup.

Signed-off-by: Martin Willi <martin@strongswan.org>
[also allow cancel scan, for completeness]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>