ARM: EXYNOS: Add framebuffer support for SMDK4X12

This patch adds framebuffer support to SMDK4212 and SMDK4412 boards.
A framebuffer window of 480x800x24bpp is defined.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>