drm/exynos/mic: workaround for disabling mic during modesetting

drm/exynos/mic: workaround for disabling mic during modesetting

Exynos-DRM framework does not power cycle encoder during modesetting, but
DRM core does it for bridges, as a result MIC device is the only
power-cycled device in the chain DECON->MIC->DSI, it causes black screen.
It is a limitation/feature of DRM core.
The patch adds ugly workaround to skip power-cycling MIC during modesetting.
Alternative is to power-cycle all components during modesetting, it would
require adjustements in ExynosDRM framework and rework of some callbacks
in DSI driver.

Change-Id: I94fdb002f119a298b35f01a4abd41d65f7d7478b
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>