mac802154: introduce mac802154_config_ops

This patch introduces mac802154_config_ops struct. Like wireless this
struct should be the only one interface between ieee802154 to mac802154
or possible HardMAC drivers.

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

diff --cc net/mac802154/Makefile
Simple merge

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

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

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