ARM: dts: exynos4212-tab3: add samsung,invert-vclk flag to fimd

After more investigation, I've found that it's not the panel driver
config that needs to be modified to invert the data polarity, but
the FIMD config.

Add the missing invert-vclk option that is required to get the display
to work correctly.

Fixes: ee37a457af1d ("ARM: dts: exynos: Add Samsung Galaxy Tab 3 8.0 boards")
Signed-off-by: Artur Weber <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Krzysztof Kozlowski <[e-mail]>

arch/arm/boot/dts/samsung/exynos4212-tab3.dtsi

···
 };
 
 &fimd {
+	samsung,invert-vclk;
 	status = "okay";
 };