mac80211: add a function for running rx without passing skbs to the stack

mac80211: add a function for running rx without passing skbs to the stack

This can be used to run mac80211 rx processing on a batch of frames in NAPI
poll before passing them to the network stack in a large batch.
This can improve icache footprint, or it can be used to pass frames via
netif_receive_skb_list.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Link: https://lore.kernel.org/r/20200726110611.46886-1-nbd@nbd.name
Signed-off-by: Johannes Berg <johannes.berg@intel.com>