ceph: pass the request to parse_reply_info_readdir()

Instead of passing just the r_reply_info to the readdir reply parser,
pass the request pointer directly instead. This will facilitate
implementing readdir on fscrypted directories.

Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-and-tested-by: Luís Henriques <lhenriques@suse.de>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>