mac80211: improve powersave documentation

There has been some confusion how drivers should implement powersave
support. Improve the documentation a bit to make it more clear what
drivers need to do. Also mention about U-APSD.

Signed-off-by: Kalle Valo <kalle.valo@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
1 file changed