PCI: hv: Switch to msi_create_parent_irq_domain()

Move away from the legacy MSI domain setup, switch to use
msi_create_parent_irq_domain().

While doing the conversion, I noticed that hv_compose_msi_msg() is doing
more than it is supposed to (composing message). This function also
allocates and populates struct tran_int_desc, which should be done in
hv_pcie_domain_alloc() instead. It works, but it is not the correct design.
However, I have no hardware to test such change, therefore I leave a TODO
note.

Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Tested-by: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: David S. Miller <davem@davemloft.net>