mac80211: remove IEEE80211_CONF_CHANGE_DYNPS_TIMEOUT

Just setting IEEE80211_CONF_CHANGE_PS should be sufficient
for changes in the power saving things. The driver already
tells us whether it wants notification of dynps via the
"have dynps support" hw flag.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Reviewed-by: Kalle Valo <kalle.valo@iki.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>