ARM: dts: exynos: Use 'hpd-gpios' instead of 'hpd-gpio'

This patch enables getting a HPD GPIO descriptor quicker.
The exynos-hdmi driver uses "hpd" for HDMI hot plug detection.

	static int hdmi_resources_init(struct hdmi_context *hdata)
	{
		...
		hdata->hpd_gpio = devm_gpiod_get(dev, "hpd", GPIOD_IN);
		...
	}

This calls 'of_find_gpio()' and it generates the GPIO consumer ID by referring
GPIO suffix. So 'hpd-gpios' is preferred on getting a GPIO descriptor.

However, if the device tree uses 'hpd-gpio', then the exynos-hdmi driver
always retries to get a GPIO descriptor because the first GPIO suffix is not
'gpio' but 'gpios'. So you always see the debug message below.

	of_get_named_gpiod_flags: can't parse 'hpd-gpios' property of node '/soc/hdmi@14530000[0]'

Use the preferred property, 'hpd-gpios' instead of 'hpd-gpio'.

Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Cc: devicetree@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Milo Kim <woogyom.kim@gmail.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
diff --git a/arch/arm/boot/dts/exynos5250-arndale.dts b/arch/arm/boot/dts/exynos5250-arndale.dts
index ea70603..3d981f3 100644
--- a/arch/arm/boot/dts/exynos5250-arndale.dts
+++ b/arch/arm/boot/dts/exynos5250-arndale.dts
@@ -152,7 +152,7 @@
 };
 
 &hdmi {
-	hpd-gpio = <&gpx3 7 GPIO_ACTIVE_LOW>;
+	hpd-gpios = <&gpx3 7 GPIO_ACTIVE_LOW>;
 	vdd_osc-supply = <&ldo10_reg>;
 	vdd_pll-supply = <&ldo8_reg>;
 	vdd-supply = <&ldo8_reg>;