drm/exynos/mic: use mode info stored in CRTC to detect i80 mode

MIC driver should use info from CRTC to check mode of work instead of
illegally peeking into nodes of other devices.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>