crypto: scatterwalk - Remove obsolete PageSlab check

As it is now legal to call flush_dcache_page on slab pages we
no longer need to do the check in the Crypto API.

Reported-by: Ira Weiny <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

include/crypto/scatterwalk.h

···
 		struct page *page;
 
 		page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT);
-		/* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as
-		 * PageSlab cannot be optimised away per se due to
-		 * use of volatile pointer.
-		 */
-		if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page))
-			flush_dcache_page(page);
+		flush_dcache_page(page);
 	}
 
 	if (more && walk->offset >= walk->sg->offset + walk->sg->length)