Since the sysfs attribute hangs off the RMI bus, which doesn't go away during
firmware flash, it needs to be explicitly removed, otherwise we would try and
register the same attribute twice.

This reverts commit 36a44af5.
Signed-off-by: Nick Dyer <nick@shmanahar.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>