regmap: use debugfs even when no device

This registers regmaps with debugfs even when they do not have an
associated device. For example, this is common for syscon regmaps.

Signed-off-by: David Lechner <david@lechnology.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/base/regmap/regmap.c

@@ -1116,6 +1116,8 @@ skip_format_initialization:
 		ret = regmap_attach_dev(dev, map, config);
 		if (ret != 0)
 			goto err_regcache;
+	} else {
+		regmap_debugfs_init(map, config->name);
 	}
 
 	return map;