the work has been scheduled from interrupt, and not been
cancelled when the driver is unloaded, which doesn't remove
the work item from the global workqueue. call the
cancel_work_sync when the driver is removed (rmmod'ed).

Cc: Sriram <srk@ti.com>
Cc: Cyril Chemparathy <cyril@ti.com>
Cc: Vinay Hegde <vinay.hegde@ti.com>
Signed-off-by: Devendra Naga <devendra.aaru@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>