net: dsa: be louder when a non-legacy FDB operation fails

The dev_close() call was added in commit c9eb3e0f

 ("net: dsa: Add
support for learning FDB through notification") "to indicate inconsistent
situation" when we could not delete an FDB entry from the port.

bridge fdb del d8:58:d7:00:ca:6d dev swp0 self master

It is a bit drastic and at the same time not helpful if the above fails
to only print with netdev_dbg log level, but on the other hand to bring
the interface down.

So increase the verbosity of the error message, and drop dev_close().

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