net: dsa: felix: perform teardown in reverse order of setup

In general it is desirable that cleanup is the reverse process of setup.
In this case I am not seeing any particular issue, but with the
introduction of devlink-sb for felix, a non-obvious decision had to be
made as to where to put its cleanup method. When there's a convention in
place, that decision becomes obvious.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>