drm/ast: 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
ast.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210803125928.27780-3-tzimmermann@suse.de

drivers/gpu/drm/ast/ast_mode.c

@@ -808,7 +808,7 @@ ast_cursor_plane_helper_atomic_update(struct drm_plane *plane,
 		ast_cursor_plane->hwc[ast_cursor_plane->next_hwc_index].map;
 	u64 dst_off =
 		ast_cursor_plane->hwc[ast_cursor_plane->next_hwc_index].off;
-	struct dma_buf_map src_map = shadow_plane_state->map[0];
+	struct dma_buf_map src_map = shadow_plane_state->data[0];
 	unsigned int offset_x, offset_y;
 	u16 x, y;
 	u8 x_offset, y_offset;