drm/vmwgfx: Add support for CursorMob and CursorBypass 4

* Add support for CursorMob
* Add support for CursorBypass 4
* Refactor vmw_du_cursor_plane_atomic_update to be kms-helper-atomic
  -- move BO mappings to vmw_du_cursor_plane_prepare_fb
  -- move BO unmappings to vmw_du_cursor_plane_cleanup_fb

Cursor mobs are a new svga feature which enables support for large
cursors, e.g. large accessibility cursor on platforms with vmwgfx. It
also cleans up the cursor code and makes it more uniform with the rest
of modern guest backed objects support.

Signed-off-by: Martin Krastev <krastevm@vmware.com>
Reviewed-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Maaz Mombasawala <mombasawalam@vmware.com>
Signed-off-by: Zack Rusin <zackr@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220302152426.885214-2-zack@kde.org