dt-bindings: irqchip: ti,sci-inta: Fix warning for missing #interrupt-cells

ti,sci-inta nodes, or else we will have following warning when building
device tree files with W=2 warning level.

arch/arm64/boot/dts/ti/k3-j721e-main.dtsi:147.51-156.5: Warning (interrupt_provider): /bus@100000/main-navss/interrupt-controller@33d00000: Missing #interrupt-cells in interrupt provider

And further, #interrupt-cells is required to be in yaml bindings as well
to prevent following schema warnings:

k3-j721e-common-proc-board.dtb: interrupt-controller@33d00000: Unevaluated properties are not allowed ('#interrupt-cells' was unexpected)
>From schema: linux/Documentation/devicetree/bindings/interrupt-controller/ti,sci-inta.yaml

Add #interrupt-cells property in ti,sci-inta.yaml

Signed-off-by: Apurva Nandan <a-nandan@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220819190729.32358-2-a-nandan@ti.com