dt-bindings: interrupt-controller: arm,gic-v3: Fix 'interrupts' cell size in example

The 2nd example has an interrupts cells size of 4, but the 'interrupts'
property has 3 cells. The example should also be separate since the cell
size differs in each example.

Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220106182518.1435497-5-robh@kernel.org