backlight: apple_bl: Deprecate pci_get_bus_and_slot()

pci_get_bus_and_slot() is restrictive such that it assumes domain=0 as
where a PCI device is present. This restricts the device drivers to be
reused for other domain numbers.

Getting ready to remove pci_get_bus_and_slot() function in favor of
pci_get_domain_bus_and_slot().

Hard-coding the domain as 0.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Jingoo Han <jingoohan1@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>