DynamicTablesPkg/HwInfoParserLib: Reject PPI partitions

PPI partitions are not supported by the FDT hardware information
parser. These may be used to describe TRBE interrupts.
Detect a ppi-partitions child node under the CPU interrupt
controller and return EFI_UNSUPPORTED before parsing GIC
information.

Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>