driver core: remove DEVICE_NAME_SIZE define

There is no such thing as a "device name size" in the driver core, so
remove the define and fix up any users of this odd define in the rest of
the kernel.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>