mac80211: mark station unauthorized before key removal

If a station is still marked as authorized, mark it as no longer
so before removing its keys. This allows frames transmitted to it
to be rejected, providing additional protection against leaking
plain text data during the disconnection flow.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200326155133.ccb4fb0bb356.If48f0f0504efdcf16b8921f48c6d3bb2cb763c99@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>