mac80211: minstrel_ht: increase stats update interval

The shorter interval was leading to too many frames being used for probing

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20210115120242.89616-9-nbd@nbd.name


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