mac80211: remove unused flags argument in transmit functions

The flags argument in transmit functions is no longer being used
and can be removed.

Signed-off-by: Mathy Vanhoef <Mathy.Vanhoef@kuleuven.be>
Link: https://lore.kernel.org/r/20200723100153.31631-5-Mathy.Vanhoef@kuleuven.be


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