wifi: mac80211: introduce a feature flag for quiet in CSA

When doing CSA in multi-link, there really isn't a need to
stop transmissions entirely. Add a feature flag for drivers
to indicate they can handle quiet in CSA (be it by parsing
themselves, or by implementing drv_pre_channel_switch()),
to make that possible.

Also clean up the csa_block_tx handling: it clearly cannot
handle multi-link due to the way queues are stopped, move
it to the sdata. Drivers should be doing it themselves for
working properly during CSA in MLO anyway. Also rename it
to indicate that it reflects TX was blocked at mac80211.

Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240228095719.258439191541.I2469d206e2bf5cb244cfde2b4bbc2ae6d1cd3dd9@changeid


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