drm/exynos: kill pipe field from drivers contexts

Since possible_crtcs are set by Exynos core helper pipe fields have no
raison d'etre. The only place it was used, as a hack, is
fimd_clear_channels, to avoid calling drm_crtc_handle_vblank, but DRM core
has already other protection mechanism (vblank->enabled), so it could be
safely removed.

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

drivers/gpu/drm/exynos/exynos_mixer.c

@@ -99,7 +99,6 @@ struct mixer_context {
 	struct drm_device	*drm_dev;
 	struct exynos_drm_crtc	*crtc;
 	struct exynos_drm_plane	planes[MIXER_WIN_NR];
-	int			pipe;
 	unsigned long		flags;
 
 	struct mixer_resources	mixer_res;
@@ -900,7 +899,6 @@ static int mixer_initialize(struct mixer_context *mixer_ctx,
 	priv = drm_dev->dev_private;
 
 	mixer_ctx->drm_dev = drm_dev;
-	mixer_ctx->pipe = drm_dev->mode_config.num_crtc;
 
 	/* acquire resources: regs, irqs, clocks */
 	ret = mixer_resources_init(mixer_ctx);