PCI: Move prototypes for pci_bus_find_capability to include/linux/pci.h

We need pci_bus_find_capability() in some arch/powerpc code so move
the prototype into a header accessible to it.

Also kill the duplicate prototype for pci_bus_alloc_resource().

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>