ap: disable power management

(cherry picked from commit 999ff0eec6a0088bd045d96d13c8ff1ace75a3bf)
ap: add support for setting txpower via Puavo tags

(cherry picked from commit 1c4ae490fb1fde8752d85313d2776596a2e9e5b7)
ap: add support for setting txpower of 5GHz interfaces separately

(cherry picked from commit f5e0465a6451b34fabdf6d390f1f8a1b49244a56)