mac802154: use put and get unaligned functions

This patch removes the swap pointer and memmove functionality. Instead
we use the well known put/get unaligned access with specific byte order
handling.

Signed-off-by: Alexander Aring <aar@pengutronix.de>
Suggested-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>