802.15.4 Soft MAC 2015 version support

[zephyrbot]

Reported by Andrei Laperie:

The Zephyr IP Stack needs 802.15.4 Soft MAC support.

• 802.15.4 - LLDN frame support #2401: 802.15.4 - LLDN frame support
• 802.15.4 - Multipurpose frame support #2400: 802.15.4 - Multipurpose frame support
• 802.15.4 - TSCH Radio protocol support #2399: 802.15.4 - TSCH Radio protocol support
• 802.15.4 - Update existing Management commands #2398: 802.15.4 - Update existing Management commands
• 802.15.4 - IE list support #2397: 802.15.4 - IE list support
• 802.15.4 - Management service: FFD level support #2396: 802.15.4 - Management service: FFD level support

(Imported from Jira ZEP-2275)

[zephyrbot]

References GH-2358

[laperie]

Looks like we won't implement that any time soon, hence closing