DynamicTablesPkg: AcpiSsdtPcieLibArm: Remove link device generation

DynamicTablesPkg: AcpiSsdtPcieLibArm: Remove link device generation

In ACPI 6.4, s6.2.13, _PRT objects describing PCI legacy interrupts
can be defined following 2 models.
In the first model, _PRT entries reference link devices. Link devices
then describe interrupts. This allows to dynamically modify
interrupts through _SRS and _PRS objects and to choose exactly the
interrupt type (level/edge triggered, active high/low).
In the second model, interrupt numbder are described in the _PRT entry.
The interrupt type is then assumed by the OS.

The Arm BSA, sE.6 "Legacy interrupts" states that PCI legacy
interrupts must be converted to SPIs, and programmed level-sensitive,
active high. Thus any OS must configure interrupts as such and there
is no need to specify the interrupt type.
Plus it is not possible to dynamically configure PCI interrupts.

Thus remove the link device generation and use the second model
for _PRT.

Suggested-by: Ard Biesheuvel <ardb+tianocore@kernel.org>
Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>