nl80211: fix NL80211_ATTR_FTM_RESPONDER policy

nl80211: fix NL80211_ATTR_FTM_RESPONDER policy

BugLink: https://bugs.launchpad.net/bugs/1874111
commit 0e012b4e4b5ec8e064be3502382579dd0bb43269 upstream.

The nested policy here should be established using the
NLA_POLICY_NESTED() macro so the length is properly
filled in.

Cc: stable@vger.kernel.org
Fixes: 81e54d08d9d8 ("cfg80211: support FTM responder configuration/statistics")
Link: https://lore.kernel.org/r/20200412004029.9d0722bb56c8.Ie690bfcc4a1a61ff8d8ca7e475d59fcaa52fb2da@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>