kernel/main: fix calling sysfs_notify from atomic context

Sysfs_notify takes a mutex and therefore cannot be called from atomic
context like interrupt handler in this case. Use a workqueue to schedule
the work instead.

Change-Id: I0a5230fe379aa51f1065df4af9b27f471aa22440
Signed-off-by: Amar Singhal <asinghal@codeaurora.org>