ARM: EXYNOS: Invert VCLK polarity for framebuffer on ORIGEN

Framebuffer driver needs to fetch the video data during the rising
edge of the VCLK. Otherwise, there are some glitches in the LCD
display.

Signed-off-by: Tushar Behera <tushar.behera@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>