vmstate-static-checker: update whitelist

Commit 22382bb96c8bd88370c1ff0cb28c3ee6bee79ed3 renamed the
'hw_cursor_x' and 'hw_cursor_y' fields in cirrus_vga.  Update the static
checker's whitelist to allow matching against the old and new names.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
