libceph: generalize ceph_pg_mapping

In preparation for adding support for primary_temp mappings, generalize
struct ceph_pg_mapping so it can hold mappings other than pg_temp.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Alex Elder <elder@linaro.org>

net/ceph/debugfs.c

@@ -88,9 +88,9 @@ static int osdmap_show(struct seq_file *s, void *p)
 
 		seq_printf(s, "pg_temp %llu.%x [", pg->pgid.pool,
 			   pg->pgid.seed);
-		for (i = 0; i < pg->len; i++)
+		for (i = 0; i < pg->pg_temp.len; i++)
 			seq_printf(s, "%s%d", (i == 0 ? "" : ","),
-				   pg->osds[i]);
+				   pg->pg_temp.osds[i]);
 		seq_printf(s, "]\n");
 	}