IDLETIMER: We shouldn't sleep in the timer routine

Currently, IDLETIMER timer routine calls kobject_uevent, which might sleep.
Since we are in interrupt context, we now schedule a work when the timer
expires. This calls sysfs_notify() for notifying userspace.

Signed-off-by: Samuel Ortiz <samuel.ortiz@solidboot.com>
Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com>