drm/cirrus: Use offset-adjusted shadow-plane mappings

For framebuffers with non-zero offset fields, shadow-plane helpers
provide a pointer to the first byte of the contained data. Use it in
cirrus.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210803125928.27780-7-tzimmermann@suse.de

drivers/gpu/drm/tiny/cirrus.c

@@ -435,7 +435,7 @@ static void cirrus_pipe_enable(struct drm_simple_display_pipe *pipe,
 	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
 
 	cirrus_mode_set(cirrus, &crtc_state->mode, plane_state->fb);
-	cirrus_fb_blit_fullscreen(plane_state->fb, &shadow_plane_state->map[0]);
+	cirrus_fb_blit_fullscreen(plane_state->fb, &shadow_plane_state->data[0]);
 }
 
 static void cirrus_pipe_update(struct drm_simple_display_pipe *pipe,
@@ -451,7 +451,7 @@ static void cirrus_pipe_update(struct drm_simple_display_pipe *pipe,
 		cirrus_mode_set(cirrus, &crtc->mode, state->fb);
 
 	if (drm_atomic_helper_damage_merged(old_state, state, &rect))
-		cirrus_fb_blit_rect(state->fb, &shadow_plane_state->map[0], &rect);
+		cirrus_fb_blit_rect(state->fb, &shadow_plane_state->data[0], &rect);
 }
 
 static const struct drm_simple_display_pipe_funcs cirrus_pipe_funcs = {