ARM: dts: uniphier: Remove compatible "snps,dw-pcie-ep" from pcie-ep node

The generic platform driver pcie-designware-plat.c doesn't work for
UniPhier PCIe endpoint controller, because the controller has some
necessary initialization sequence for the controller-specific logic.

Currently the controller doesn't use "snps,dw-pcie-ep" compatible,
so this is no longer needed. Remove the compatible string from the
pcie-ep node.

Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@socionext.com>
Link: https://lore.kernel.org/r/20220913042249.4708-10-hayashi.kunihiko@socionext.com

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Signed-off-by: Arnd Bergmann <arnd@arndb.de>