mac802154: Prepare forcing specific symbol duration

The scan logic will bypass the whole ->set_channel() logic from the top
by calling the driver hook to just switch between channels when
required.

We can no longer rely on the "current" page/channel settings to set the
right symbol duration. Let's add these as new parameters to allow
providing the page/channel couple that we want.

There is no functional change.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Alexander Aring <aahringo@redhat.com>
Link: https://lore.kernel.org/r/20230103165644.432209-5-miquel.raynal@bootlin.com


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