pci: Move some PCIe register offset definitions to a common header

pci: Move some PCIe register offset definitions to a common header

Some PCI Express register offsets are currently defined in multiple
drivers, move them to a common header to avoid re-definitions and
as a pre-requisite for adding new PCIe driver.
While at it replace some spaces with tabs.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>