ieee802154: Define a beacon frame header

This definition will be used when adding support for scanning and defines
the content of a beacon frame header as in the 802.15.4 specification.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20230103165644.432209-3-miquel.raynal@bootlin.com


Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>