mac80211: add rate control support for encap offload

The software rate control cannot deal with encap offload, so fix it.

Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Link: https://lore.kernel.org/r/20210617163113.75815-3-nbd@nbd.name


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