PCI: uniphier-ep: Add NX1 support

Add basic support for UniPhier NX1 SoC as non-legacy SoC. This includes
a compatible string, SoC-dependent data containing init() and wait()
functions for the controller.

Link: https://lore.kernel.org/r/1644480596-20037-4-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>