dt-bindings: mfd: logicvc: Add patternProperties for the display

The LogiCVC multi-function device has a display part which is now
described in its binding. Add a patternProperties match for it.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>