PCI: uniphier: Add Socionext UniPhier Pro5 PCIe endpoint controller driver

Add driver for the Socionext UniPhier Pro5 SoC endpoint controller.
This controller is based on the DesignWare PCIe core.

And add "host" to existing controller descriontions for the host controller
in Kconfig.

Link: https://lore.kernel.org/r/1589457801-12796-3-git-send-email-hayashi.kunihiko@socionext.com


Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>