Revert "ath9k: fix going to full-sleep on PS idle"

This reverts commit c1afdaff.

Users have reported connection failures in 3.3.1 and suspend/resume
failures in 3.4-rcX. Revert this commit for now - PS IDLE can be
fixed in a clean manner later on.

Cc: stable@vger.kernel.org
Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>