ieee802154: 6lowpan: remove packet type to host

This patch remove the packet_type to host and leave the mac pkt_type.
By running 'grep -r "pkt_type" net/ipv6', the IPv6 stack will evaluate
this value for PACKET_BROADCAST. Instead of overwriting this value we
will leave the mac value there which is broadcasts if the mac frame was
a broadcast frame.

Reviewed-by: Stefan Schmidt <stefan@osg.samsung.com>
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>