The GPC node references an interrupt parent, but it doesn't
state the interrupt itself. According to the TRM, this IRQ
is 87. This also eliminate an error detected from dt_binding_check
Fixes: fc0f05124621 ("arm64: dts: imx8mp: add GPC node with GPU power domains") Signed-off-by: Adam Ford <aford173@gmail.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Shawn Guo <shawnguo@kernel.org>