iort_get_device_domain() is PCI specific but it need not be,
since it can be used to retrieve IRQ domain nexus of any kind
by adding an irq_domain_bus_token input to it.

Make it PCI agnostic by also renaming the requestor ID input
to a more generic ID name.
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>   # pci/msi.c
Cc: Will Deacon <will@kernel.org>
Cc: Hanjun Guo <guohanjun@huawei.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Link: https://lore.kernel.org/r/20200619082013.13661-3-lorenzo.pieralisi@arm.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>