MIPS: mscc: ocelot: disable all switch ports by default

The ocelot switch driver used to ignore ports which do not have a
phy-handle property and not probe those, but this is not quite ok since
it is valid to not have a phy-handle property if there is a fixed-link.

It seems that checking for a phy-handle was a proxy for the proper check
which is for the status, but that doesn't make a lot of sense, since the
ocelot driver already iterates using for_each_available_child_of_node
which skips the disabled ports, so I have no idea.

Anyway, a widespread pattern in device trees is for a SoC dtsi to
disable by default all hardware, and let board dts files enable what is
used. So let's do that and enable only the ports with a phy-handle in
the pcb120 and pcb123 device tree files.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>