drm: Remove internal setup of struct drm_device.vblank_disable_immediate

VBLANK interrupts can be disabled immediately or with a delay, where the
latter is the default. The former option can be selected by setting
get_vblank_timestamp and enabling vblank_disable_immediate in struct
drm_device. Simplify the code in preparation of the removal of struct
drm_device.get_vblank_timestamp.

v3:
	* remove internal setup of vblank_disable_immediate
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200123135943.24140-2-tzimmermann@suse.de

drivers/gpu/drm/drm_vblank.c

@@ -486,19 +486,6 @@ int drm_vblank_init(struct drm_device *dev, unsigned int num_crtcs)
 
 	DRM_INFO("Supports vblank timestamp caching Rev 2 (21.10.2013).\n");
 
-	/* Driver specific high-precision vblank timestamping supported? */
-	if (dev->driver->get_vblank_timestamp)
-		DRM_INFO("Driver supports precise vblank timestamp query.\n");
-	else
-		DRM_INFO("No driver support for vblank timestamp query.\n");
-
-	/* Must have precise timestamping for reliable vblank instant disable */
-	if (dev->vblank_disable_immediate && !dev->driver->get_vblank_timestamp) {
-		dev->vblank_disable_immediate = false;
-		DRM_INFO("Setting vblank_disable_immediate to false because "
-			 "get_vblank_timestamp == NULL\n");
-	}
-
 	return 0;
 
 err: