Bits 2 and 3 (\3 and \4 of the %b flag mask) are the 'Supported Channel
Width Set' indicating VHT160 (B2) or VHT160 and VHT80P80 (B3) support.
Though longer rename \4 from CHAN80P80 to CHAN160+80P80 to not confuse
the reader that VHT160 might not be supported.
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