PCI: Discard __init annotations for pci_fixup_irqs() and related functions

Remove the __init annotations in order to keep pci_fixup_irqs() around
after init (e.g. for hotplug). This requires the same change for the
implementation of pcibios_update_irq() on all architectures. While at
it, all __devinit annotations are removed as well, since they will be
useless now that HOTPLUG is always on.

Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>