video: support DP controller driver

Samsung EXYNOS SoC such Exynos5 has DP controller and embedded DP
panel can be used. This patch supports DP driver based on Samsung
EXYNOS SoC chip.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>