ARM: dts: fix clock-frequency of display timing0 for exynos3250-rinato

After the commit abc0b144 ("drm: Perform basic sanity checks on
probed modes"), proper clock-frequency becomes mandatory for
validating the mode of panel.  The display does not work if there is
no mode validated. Also, this clock-frequency must be set
appropriately for getting required frame rate.

Fixes: abc0b144 ("drm: Perform basic sanity checks on probed modes")
Cc: <stable@vger.kernel.org>
Signed-off-by: Hyungwon Hwang <human.hwang@samsung.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Sigend-off-by: Kukjin Kim <kgene@kernel.org>

arch/arm/boot/dts/exynos3250-rinato.dts

@@ -182,7 +182,7 @@ panel@0 {
 
 		display-timings {
 			timing-0 {
-				clock-frequency = <0>;
+				clock-frequency = <4600000>;
 				hactive = <320>;
 				vactive = <320>;
 				hfront-porch = <1>;