crush: merge working data and scratch

Much like Arlo Guthrie, I decided that one big pile is better than two
little piles.

Reflects ceph.git commit 95c2df6c7e0b22d2ea9d91db500cf8b9441c73ba.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

include/linux/ceph/osdmap.h

@@ -173,8 +173,7 @@ struct ceph_osdmap {
 	 * the list of osds that store+replicate them. */
 	struct crush_map *crush;
 
-	struct mutex crush_scratch_mutex;
-	int crush_scratch_ary[CEPH_PG_MAX_SIZE * 3];
+	struct mutex crush_workspace_mutex;
 	void *crush_workspace;
 };