drm/exynos: remove DRM_FORMAT_NV12M from plane module

this patch removes DRM_FORMAT_NV12M from plane module because this format
is same as DRM_FORMAT_NV12. DRM_FORMAT_NV12M will be identified by
mode_cmd->handles and mode_cmd->offsets fields internally.

Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Kyungmin.park <kyungmin.park@samsung.com>
diff --git a/drivers/gpu/drm/exynos/exynos_drm_plane.c b/drivers/gpu/drm/exynos/exynos_drm_plane.c
index b89829e..e1f94b7 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_plane.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_plane.c
@@ -29,7 +29,6 @@
 	DRM_FORMAT_XRGB8888,
 	DRM_FORMAT_ARGB8888,
 	DRM_FORMAT_NV12,
-	DRM_FORMAT_NV12M,
 	DRM_FORMAT_NV12MT,
 };