USB: move many drivers to use DEVICE_ATTR_RO

Instead of "open coding" a DEVICE_ATTR() define, use the
DEVICE_ATTR_RO() macro instead, which does everything properly instead.

This does require a few static functions to be renamed to work properly,
but thanks to a script from Joe Perches, this was easily done.

Reported-by: Joe Perches <joe@perches.com>
Cc: Matthieu CASTET <castet.matthieu@free.fr>
Cc: Stanislaw Gruszka <stf_xl@wp.pl>
Cc: Oliver Neukum <oneukum@suse.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>