drm/exynos: Merge pre/postclose hooks

Again no apparent explanation for the split except hysterical raisins.
Merging them also makes it a bit more obviuos what's going on wrt the
runtime pm refdancing.

Cc: Inki Dae <inki.dae@samsung.com>
Cc: Joonyoung Shim <jy0922.shim@samsung.com>
Cc: Seung-Woo Kim <sw0312.kim@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: NSean Paul <seanpaul@chromium.org>
Reviewed-by: NLiviu Dudau <Liviu.Dudau@arm.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170508082633.4214-3-daniel.vetter@ffwll.ch

drivers/gpu/drm/exynos/exynos_drm_drv.c

@@ -82,14 +82,9 @@ static int exynos_drm_open(struct drm_device *dev, struct drm_file *file)
 	return ret;
 }
 
-static void exynos_drm_preclose(struct drm_device *dev,
-					struct drm_file *file)
-{
-	exynos_drm_subdrv_close(dev, file);
-}
-
 static void exynos_drm_postclose(struct drm_device *dev, struct drm_file *file)
 {
+	exynos_drm_subdrv_close(dev, file);
 	kfree(file->driver_priv);
 	file->driver_priv = NULL;
 }
@@ -145,7 +140,6 @@ static struct drm_driver exynos_drm_driver = {
 	.driver_features	= DRIVER_MODESET | DRIVER_GEM | DRIVER_PRIME
 				  | DRIVER_ATOMIC | DRIVER_RENDER,
 	.open			= exynos_drm_open,
-	.preclose		= exynos_drm_preclose,
 	.lastclose		= exynos_drm_lastclose,
 	.postclose		= exynos_drm_postclose,
 	.gem_free_object_unlocked = exynos_drm_gem_free_object,