sparc64: Skip bogus PCI bridge ranges.

It seems that when a PCI Express bridge is not in use and has no devices
behind it, the ranges property is bogus.  Specifically the size property
is of the form [0xffffffff:...], and if you add this size to the resource
start address the 64-bit calculation will overflow.

Just check specifically for this size value signature and skip them.

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