[PATCH] w1: cleanups.

 - white space changes.
 - list_for_each_entry/list_for_each_entry_safe and reverse changes.
 - small coding style changes.
 - removed redundant NULL checks.
 - use attribute group and macros instead of direct device attributes.
Patch is havily based on work from Adrian Bunk and Dmitry Torokhov,
thanks guys.

Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>