mac80211: minstrel_ht: fix regression in the max_prob_rate fix

Since mi->max_prob_rate is overwritten after the loop that calls
minstrel_ht_set_best_prob_rate, the new best rate needs to be written to *dest

Fixes: a7fca4e4 ("mac80211: minstrel_ht: fix max probability rate selection")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20210126154409.6755-1-nbd@nbd.name


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