The Rockchip PCIe controller DT binding clearly states that 'ep-gpios' is
an optional property. And indeed there are boards that don't require it.
Make the driver follow the binding by using devm_gpiod_get_optional()
instead of devm_gpiod_get().
[bhelgaas: tidy whitespace]
Link: https://lore.kernel.org/r/20210121162321.4538-2-wens@kernel.org
Fixes: e77f847df5 ("PCI: rockchip: Add Rockchip PCIe controller support")
Fixes: 956cd99b35 ("PCI: rockchip: Separate common code from RC driver")
Fixes: 964bac9455 ("PCI: rockchip: Split out rockchip_pcie_parse_dt() to parse DT")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
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