wifi: mac80211: rework RX timestamp flags

We only have a single flag free, and before using that for
another mactime flag, instead refactor the mactime flags
to use a 2-bit field.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Gregory Greenman <gregory.greenman@intel.com>
Reviewed-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20231220133549.d0e664832d14.I20c8900106f9bf81316bed778b1e3ce145785274@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>