sh: Revert lazy dcache writeback changes.

These ended up causing too many problems on older parts,
revert for now..

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/mm/cache-sh4.c b/arch/sh/mm/cache-sh4.c
index e0cd4b7..981b040 100644
--- a/arch/sh/mm/cache-sh4.c
+++ b/arch/sh/mm/cache-sh4.c
@@ -237,20 +237,10 @@
 /*
  * Write back & invalidate the D-cache of the page.
  * (To avoid "alias" issues)
- *
- * This uses a lazy write-back on UP, which is explicitly
- * disabled on SMP.
  */
 void flush_dcache_page(struct page *page)
 {
-#ifndef CONFIG_SMP
-	struct address_space *mapping = page_mapping(page);
-
-	if (mapping && !mapping_mapped(mapping))
-		set_bit(PG_dcache_dirty, &page->flags);
-	else
-#endif
-	{
+	if (test_bit(PG_mapped, &page->flags)) {
 		unsigned long phys = PHYSADDR(page_address(page));
 		unsigned long addr = CACHE_OC_ADDRESS_ARRAY;
 		int i, n;