video: exynos mipi dsi: Fix mipi dsi regulators handling issue

When FB_BLANK_UNLANK event occured, exynos mipi dsi regulators have to turn on.

Signed-off-by: Donghwa Lee <dh09.lee@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>