dt-bindings: interrupt-controller: update bindings for supporting more SoCs

Update bindings for Layerscape external irqs,
support more SoCs(LS1043A, LS1046A, LS1088A,
LS208xA, LX216xA)

Signed-off-by: Biwen Li <biwen.li@nxp.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201130101515.27431-11-biwen.li@oss.nxp.com