arm64: zynqmp: Make SMMU a separate node outside amba

arm64: zynqmp: Make SMMU a separate node outside amba

Drivers dependent on IOMMU expect SMMU to be probed first and
in PM flow, suspended last and resumed first.

This can ideally be achieved by adding PM support in arm-smmu and
maintaining the above expected order. This series on LKML proposes
the same:
https://patchwork.ozlabs.org/cover/885035/

But this is still under review and would require pulling in more
framework changes on the current xilinx tree. Hence this patch
provides a temporary fix until the above solution is finalized.
The expected order is maintained by moving SMMU node outside amba node
in the devicetree.

Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>