dt-bindings: ocelot: document lan969x-pinctrl

Lan969x is going to reuse the existing Ocelot pinctrl driver - document
that by adding compatible strings for the different SKU's that we
support.

Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/20240917-lan969x-pinctrl-v2-1-ea02cbc56831@microchip.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>