mac80211: fix dropped counter in multiqueue RX

In the commit enabling per-CPU station statistics, I inadvertedly
copy-pasted some code to update rx_packets and forgot to change it
to update rx_dropped_misc. Fix that.

This addresses https://bugzilla.kernel.org/show_bug.cgi?id=195953

.

Fixes: c9c5962b ("mac80211: enable collecting station statistics per-CPU")
Reported-by: Petru-Florin Mihancea <petrum@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>