drm/tidss: Add prepare_fb to the plane helper funcs

drm_gem_fb_prepare_fb() extracts fence and attaches to plane state.
The fence info is needed if implicit fencing is used. Add this as
prepare_fb function pointer to plane helper funcs.
Signed-off-by: Gowtham Tammana <g-tammana@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200826134409.473554-1-tomi.valkeinen@ti.com

drivers/gpu/drm/tidss/tidss_plane.c

@@ -10,6 +10,7 @@
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_fb_cma_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
 
 #include "tidss_crtc.h"
 #include "tidss_dispc.h"
@@ -150,6 +151,7 @@ static void drm_plane_destroy(struct drm_plane *plane)
 }
 
 static const struct drm_plane_helper_funcs tidss_plane_helper_funcs = {
+	.prepare_fb = drm_gem_fb_prepare_fb,
 	.atomic_check = tidss_plane_atomic_check,
 	.atomic_update = tidss_plane_atomic_update,
 	.atomic_disable = tidss_plane_atomic_disable,