pci: Introduce pci_register_io_range() helper function.

Some architectures do not have a simple view of the PCI I/O space
and instead use a range of CPU addresses that map to bus addresses. For
some architectures these ranges will be expressed by OF bindings
in a device tree file.

Introduce a pci_register_io_range() helper function with a generic
implementation that can be used by such architectures to keep track
of the I/O ranges described by the PCI bindings. If the PCI_IOBASE
macro is not defined that signals lack of support for PCI and we
return an error.

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>