PCI: Consolidate calls to pcibios_bus_to_resource() in __pci_read_base()

Since we will invoke pcibios_bus_to_resource() unconditionally if we
don't goto fail, move it out of if/else wrap.  No function change.

Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>