The g5 code has special hooks to "hide" some PCI devices when they are off.

Currently, this code involves some calls to match a pci_dev from the open
firmware node and such things that are causing some problems with the
latest version of my sungem driver who wants to do some of this in atomic
contexts.

This patch moves that to a list of struct device_node instead, which also
ends up simplifying the code.

Later, I'll go back to manipulating PCI devices in a clean way when Brian
King's PCI blocking patch gets in, but only after I change sungem again to
never call these in atomic context.  This is a 3 step transition basically
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>