Merge branch 'minor-managed-neighbor-follow-ups'

Daniel Borkmann says:

====================
Minor managed neighbor follow-ups

Minor follow-up series to address prior feedback from David and Jakub.
Patch 1 adds a build time assertion to prevent overflows when shifting
in extended flags, patch 2 is a cleanup to use NLA_POLICY_MASK instead
of open-coding invalid flags rejection and patch 3 rejects creating new
neighbors with NUD_PERMANENT & NTF_MANAGED. For details, see individual
patches.
====================

Link: https://lore.kernel.org/r/20211013132140.11143-1-daniel@iogearbox.net


Signed-off-by: Jakub Kicinski <kuba@kernel.org>