ARM64: zynqmp: Add missing interrupt-parent to PMU node

ZynqMP is not using global interrupt-parent setting that's why
it has to be listed in every node separately. PMU node missed it and
this patch is adding it.

Reported-by: John Linn <John.Linn@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>