The ap poll timer restart condition was wrong. Hence the poll timer
was not restarted reliable when setting a new time interval via the
poll_timeout sysfs attribute.
Added missing timer locking.
Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Tuchscherer <ingo.tuchscherer@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>