Merge branch 'switchdev-dsa-docs'

Vladimir Oltean says:

====================
Documentation updates for switchdev and DSA

Many changes were made to the code but of course the documentation was
not kept up to date. This is an attempt to update some of the verbiage.

The documentation is still not complete, but it's time to make some more
changes to the code first, before documenting the rest.

Changes in v2:
Integrated feedback from Andrew, Florian, Tobias, Ido, George.
====================
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>