Merge branch 'rtnl-pushdown-prep'

Florian Westphal says:

====================
rtnetlink: preparation patches for further rtnl lock pushdown/removal

Patches split large rtnl_fill_ifinfo into smaller chunks
to better see which parts

1. require rtnl
2. do not require it at all
3. rely on rtnl locking now but could be converted

Changes since v3:

I dropped the 'ifalias' patch, I have a change to decouple ifalias and
rtnl mutex, I will send it once this series has been merged.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>