mac80211: fix memory overlap due to variable length param

As of now HE operation element in bss_conf includes variable length
optional field followed by other HE variable. Though the optional
field never be used, actually it is referring to next member of the
bss_conf structure which is not correct. Fix it by declaring needed
HE operation fields within bss_conf itself.

Signed-off-by: Rajkumar Manoharan <rmanohar@codeaurora.org>
Link: https://lore.kernel.org/r/1587768108-25248-2-git-send-email-rmanohar@codeaurora.org
Signed-off-by: Johannes Berg <johannes.berg@intel.com>