PCI/MSI: Let pci_msi_get_domain use struct device::msi_domain

PCI/MSI: Let pci_msi_get_domain use struct device::msi_domain

Now that we can easily find which MSI domain a PCI device is
using, use dev_get_msi_domain as a way to retrieve the information.

The original code is still used as a fallback.

Acked-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Hanjun Guo <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Cc: <[email protected]>
Cc: Yijing Wang <[email protected]>
Cc: Ma Jun <[email protected]>
Cc: Lorenzo Pieralisi <[email protected]>
Cc: Duc Dang <[email protected]>
Cc: Jiang Liu <[email protected]>
Cc: Jason Cooper <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Thomas Gleixner <[email protected]>