cfg80211: Remove wrong RNR IE validation check

Remove a wrong length check for RNR information element as it
can have arbitrary length.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Link: https://lore.kernel.org/r/20210408143224.c7eeaf1a5270.Iead7762982e941a1cbff93f68bf8b5139447ff0c@changeid


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