Implement missing functionality for handling of IPv6 next header (HBH hop-by-hop-option) which holds RPL related information.

[zephyrbot]

Reported by Ravi kumar Veeramally:

RPL related information is kept in IPv6 next header (HBH hop-by-bop) and not handled properly.

(Imported from Jira ZEP-1841)

[zephyrbot]

by Ravi kumar Veeramally:

Couple of patches (already part of net branch) fixes this issue. So closing this.

[zephyrbot]

Blocks GH-2153