sparc64: Fix D-cache flushing on swapin from SW devices.
Thanks to tip form ARM folks and Russell King. If flush_dcache_page() occurs on a swapin it will have a mapping and we'll try to defer the flush by setting the dirty bit. But when it hits update_dcache_page() we won't flush because the page won't have a mapping any more. So remove the mapping requirement in flush_dcache(). Signed-off-by: David S. Miller <email@example.com>