ieee802154: socket: put handling into one file

This patch puts all related socket handling into one file. This is just
a cleanup to do all socket handling stuff inside of one implementation
file.

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

diff --cc net/ieee802154/Makefile
Simple merge

diff --cc net/ieee802154/af802154.h
Simple merge

diff --cc net/ieee802154/af_ieee802154.c
Simple merge

diff --cc net/ieee802154/dgram.c
Simple merge

diff --cc net/ieee802154/raw.c
Simple merge