bfs: update ctime in addition to mtime when adding entries

When adding entries to a directory, POSIX generally requires that the
ctime be updated alongside the mtime.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Message-Id: <20230705190309.579783-2-jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>