wifi: mac80211: clean up HE 6 GHz and EHT chandef parsing

In the code we currently check for support 80+80, 160
and 320 channel widths, but really the way this should
be (and is otherwise) handled is that we compute the
highest channel bandwidth given there, and then cut it
down to what we support. This is also needed for wider
bandwidth OFDMA support.

Change the code to remove this limitation and always
parse the highest possible channel width.

Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240129194108.d06f85082e29.I47e68ed3d97b0a2f4ee61e5d8abfcefc8a5b9c08@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>