PCI: generic: Simplify host bridge window iteration

The switch is the only statement in the resource_list_for_each_entry()
loop, so remove unnecessary "continue" statements in the switch.  Remove
unnecessary "goto" statements and label.  Simplify checking for the
required non-prefetchable memory aperture.

No functional change intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>