alarmtimers: Remove period from alarm structure

Now that periodic alarmtimers are managed by the handler function,
remove the period value from the alarm structure and let the handlers
manage the interval on their own.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Stultz <john.stultz@linaro.org>

diff --cc include/linux/alarmtimer.h
Simple merge

diff --cc include/linux/posix-timers.h
Simple merge

diff --cc kernel/time/alarmtimer.c
Simple merge