PCI: hv: Make the code arch neutral by adding arch specific interfaces

PCI: hv: Make the code arch neutral by adding arch specific interfaces

Encapsulate arch dependencies in Hyper-V vPCI through a set of
arch-dependent interfaces. Adding these arch specific interfaces will
allow for an implementation for other architectures, such as arm64.

There are no functional changes expected from this patch.

Link: https://lore.kernel.org/r/1641411156-31705-2-git-send-email-sunilmut@linux.microsoft.com
Signed-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: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>