PCI: Switch msix_program_entries() to use pci_msix_desc_addr()

Instead of relying on the msix_entry structure for the vector number, read
it from the msi_desc.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Alexander Gordeev <agordeev@redhat.com>