dt-bindings: net: dsa: renesas,rzn1-a5psw: add interrupts description

Describe the switch interrupts (dlr, switch, prp, hub, pattern) which
are connected to the GIC.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: David S. Miller <davem@davemloft.net>