dt-binding: display: bcm2711-hdmi: Add CEC and hotplug interrupts

The CEC and hotplug interrupts were missing when that binding was
introduced, let's add them in now that we've figured out how it works.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Dave Stevenson <dave.stevenson@raspberrypi.com>