ARC: [mm] optimise VIPT dcache aliasing 2/x

Non-congruent SRC page in copy_user_page() is dcache clean in the end -
so record that fact, to avoid a subsequent extraneous flush.

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

arch/arc/mm/cache_arc700.c

@@ -742,6 +742,7 @@ void copy_user_highpage(struct page *to, struct page *from,
 	 */
 	if (clean_src_k_mappings) {
 		__flush_dcache_page(kfrom, kfrom);
+		clear_bit(PG_arch_1, &from->flags);
 	} else {
 		set_bit(PG_arch_1, &from->flags);
 	}