mac802154: introduce hw_to_local function

This patch replace the mac802154_to_priv macro with a static inline
function named hw_to_local. This brings a similar naming convention like
mac80211 stack.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

diff --cc net/mac802154/ieee802154_i.h
Simple merge

diff --cc net/mac802154/main.c
Simple merge

diff --cc net/mac802154/rx.c
Simple merge

diff --cc net/mac802154/tx.c
Simple merge