sparc: Fix resource flags for PCI children in OF device tree.

When a device is under an EBUS or ISA bus, the resource flags
don't get set properly.

Fix this by re-evaluating the resource flags at each level of
bus as we apply ranges on the way to the root.  And let PCI
override any existing flags setting, but don't let the
default flags calculator make such overrides.

Signed-off-by: David S. Miller <davem@davemloft.net>