xen: balloon: Use static attribute groups for sysfs entries
xen: balloon: Use static attribute groups for sysfs entries

Instead of manual calls of device_create_file(), device_remove_file()
and sysfs_create_group(), assign static attribute groups to the device
to register.  This simplifies the code and avoids possible races.

Signed-off-by: Takashi Iwai <4596b3305151c7ee743192a95d394341e3d3b644@suse.de>
Signed-off-by: David Vrabel <b9d45bd1f671e508cd8daa63dfc3cabb597562df@citrix.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs