DynamicTablesPkg: AcpiSsdtPcieLibArm: Added function to reserve ECAM space

DynamicTablesPkg: AcpiSsdtPcieLibArm: Added function to reserve ECAM space

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=3998

Certain OSes will complain if the ECAM config space is not reserved in
the ACPI namespace.

This change adds a function to reserve PNP motherboard resources for a
given PCI node.

Co-authored-by: Joe Lopez <joelopez@microsoft.com>
Signed-off-by: Kun Qin <kuqin12@gmail.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>
Tested-by: Sami Mujawar <sami.mujawar@arm.com>