Add arm64 Hyper-V vPCI support by implementing the arch specific
interfaces. Introduce an IRQ domain and chip specific to Hyper-v vPCI that
is based on SPIs. The IRQ domain parents itself to the arch GIC IRQ domain
for basic vector management.

[bhelgaas: squash in fix from Yang Li <yang.lee@linux.alibaba.com>:
https://lore.kernel.org/r/20220112003324.62755-1-yang.lee@linux.alibaba.com]
Link: https://lore.kernel.org/r/1641411156-31705-3-git-send-email-sunilmut@linux.microsoft.comSigned-off-by: Sunil Muthuswamy <sunilmut@microsoft.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>