netdevice: add ieee802154_ptr to net_device

netdevice: add ieee802154_ptr to net_device

This patch adds an ieee802154_ptr to the net_device structure.
Furthermore the 802.15.4 subsystem will introduce a nl802154 framework
which is similar like the nl80211 framework and a wpan_dev structure.
The wpan_dev structure will hold additional net_device attributes like
address options which are 802.15.4 specific. In the upcoming nl802154
implementation we will introduce a NL802154_FLAG_NEED_WPAN_DEV like
NL80211_FLAG_NEED_WDEV. For this flag an ieee802154_ptr in net_device is
needed. Additional we can access the wpan_dev attributes in upper layers
like IEEE 802.15.4 6LoWPAN easily. Current solution is a complicated
callback interface and getting these values over subif data structure
in mac802154.

Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>