ieee80211: add HE ext EIDs and 6 GHz capability defines

Add the HE extended element IDs and the definitions for the
HE 6 GHz band capabilities element, from Draft 5.0.

Link: https://lore.kernel.org/r/20200528213443.1a6689fe093f.Ifdc5400fb01779351354daf38663ebeea03c9ad9@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Git-commit: 8b30808d9be4183fab17f0b0e68eea88c94ff15a
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211-next.git


CRs-Fixed: 2743684
Change-Id: I6c284811cbcd0bf5beb72bad929eb2f6b1ec577c
Signed-off-by: Vinita S. Maloo <vmaloo@codeaurora.org>