mac80211: rt2x00: write registers required for reducing power consumption

mac80211: rt2x00: write registers required for reducing power consumption

Write registers required for reducing power consumption like the vendor
driver does when ADJUST_POWER_CONSUMPTION_SUPPORT is set.
This helps devices to sync at better TX/RX rates and improves overall
performance.

Signed-off-by: Tomislav Požega <pozega.tomislav@gmail.com>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
[daniel@makrotopia.org: edited commit message]
(backported from 6044682b83a08618a4d8f6791503e0cec5b9fbe5)
(rebased patches)
Signed-off-by: Jo-Philipp Wich <jo@mein.io>