wifi: mac80211: skip powersave recalc if driver SUPPORTS_DYNAMIC_PS

There are a few places that check ps_sdata and/or the dynamic
PS timeout, but they're erroneous in case SUPPORTS_DYNAMIC_PS
is set by the driver.

Skip the entire recalculation in this case so we cannot get
into those paths elsewhere, and so we simplify this for the
purpose of implementing MLO.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>