Documentation: networking: dsa: remove TODO about porting more vendor drivers

Documentation: networking: dsa: remove TODO about porting more vendor drivers

On one hand, the link is dead and therefore useless.

On the other hand, there are always more drivers to port, but at this
stage, DSA does not need to affirm itself as the driver model to use for
Ethernet-connected switches (since we already have 15 tagging protocols
supported and probably more switch families from various vendors), so
there is nothing actionable to do.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>