nl80211: add missing attribute validation for critical protocol indication

Add missing attribute validation for critical protocol fields
to the netlink policy.

Fixes: 5de17984 ("cfg80211: introduce critical protocol indication from user-space")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20200303051058.4089398-2-kuba@kernel.org


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