hw/arm/xlnx-zynqmp: Realize cluster after putting RPUs in it

hw/arm/xlnx-zynqmp: Realize cluster after putting RPUs in it

Currently the cluster implementation doesn't have any constraints
on the ordering of realizing the TYPE_CPU_CLUSTER and populating it
with child objects. We want to impose a constraint that realize
must happen only after all the child objects are added, so move
the realize of rpu_cluster. (The apu_cluster is already
realized after child population.)

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Luc Michel <luc.michel@greensocs.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 20190121152218.9592-2-peter.maydell@linaro.org