drm/exynos: remove color bar pattern operation.

This patch removes color bar pattern register because we don't use the register anymore.
because it doesn't support color bar feature for writeback operation.
camera driver only supports color bar feature. but IPP doesn't support camera driver.

Signed-off-by: JoongMock Shin <jmock.shin@samsung.com>
Signed-off-by: Eunchul Kim <chulspro.kim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>