ARM: Fix cache cleaning operation.

There was no behavior defined for OP_DCCSW in dcache_op_set_way, so it
silently did nothing. Since we started using that to clean the cache between
stages and I have a change that enables caches earlier on, this was preventing
booting on pit.

BUG=chrome-os-partner:19420
TEST=Built and booted on pit.
BRANCH=None

Change-Id: I3615b6569bf8de195d19d26b62f02932322b7601
Signed-off-by: Gabe Black <gabeblack@google.com>
Reviewed-on: https://gerrit.chromium.org/gerrit/66234
Reviewed-by: David Hendricks <dhendrix@chromium.org>
Commit-Queue: Gabe Black <gabeblack@chromium.org>
Tested-by: Gabe Black <gabeblack@chromium.org>

src/arch/armv7/cache.c

@@ -143,6 +143,9 @@ static void dcache_op_set_way(enum dcache_op op)
 			case OP_DCISW:
 				dcisw(val);
 				break;
+			case OP_DCCSW:
+				dccsw(val);
+				break;
 			default:
 				break;
 			}