Driver core: device_attribute parameters can often be const*

Most device_attributes are const, and are begging to be
put in a ro section. However, the create and remove
file interfaces were failing to propagate the const promise
which the only functions they call offer.

Signed-off-by: Phil Carmody <ext-phil.2.carmody@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>