[NET]: net-sysfs - use attribute group instead of kobject for statistics.

[NET]: net-sysfs - use attribute group instead of kobject for statistics.

Net statistics were in a kobject only because there was no better way
to create a directory.  Latest 2.6.0-test3 bk tree, has merged in
Pat's change to provide 'attribute groups'.

This patch converts netdevice's from a statistic's kobject to attribute
group.  This is cleaner and fixes some shutdown unload issues as well.

Ps. it gets rid of of the object