mac80211: add recalc PS in ieee80211_reconfig()

Driver should be instructed to enter PS AFTER
reconfiguring ASSOCIATED (in STA case) using ieee80211_bss_info_change_notify
same as it's being done in ieee80211_set_associated()

Signed-off-by: Eyal Shapira <eyal@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>