mac80211: minstrel_ht: remove sample rate switching code for constrained devices

mac80211: minstrel_ht: remove sample rate switching code for constrained devices

This was added to mitigate the effects of too much sampling on devices that
use a static global fallback table instead of configurable multi-rate retry.
Now that the sampling algorithm is improved, this code path no longer performs
any better than the standard probing on affected devices.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20210127055735.78599-6-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>