Revert "ath9k: Group Key fix for VAPs"

This reverts commit 03ceedea, since it
breaks resume from suspend-to-ram on Rafael's Acer Ferrari One.
NetworkManager thinks everything is ok, but it can't connect to the AP
to get an IP address after the resume.

In fact, it even breaks resume for non-ath9k chipsets: reverting it also
fixes Rafael's Toshiba Protege R500 with the iwlagn driver.  As Johannes
says:

  "Indeed, this patch needs to be reverted. That mac80211 change is wrong
   and completely unnecessary."

Reported-and-requested-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Cc: Daniel Yingqiang Ma <yma.cool@gmail.com>
Cc: John W. Linville <linville@tuxdriver.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>