From: David Woodhouse <dwmw2@infradead.org>
Date: Mon, 04 May 2009 11:32:16 +0100

I don't have to explicitly remove the files, do I? They go away
naturally when the device is unregistered?

I'm not so sure about this.  I can't see anything in the
drivers/base/core.c code that automatically deletes anything
other than device groups and attributes.