Fix a race condition during alarm_cleanup()

Fix a race condition inside function alarm_cleanup() that
could be triggered during shutdown.

Also, fix few other issues:
 * Add missing "timer_delete(akeup_timer)" statement inside
   alarm_cleanup()
 * Fix the argument when calling "timer_delete(timer)"
 * Call "semaphore_free(alarm_expired)" inside alarm_cleanup()
   after the corresponding "timer" and "wakeup_timer" have
   been deleted.
 * Fix the argument type when calling eventfd_read() inside
   semaphore_wait()

Bug: 26982349
Change-Id: I2b00cd7ee7f56f755775f8e7b370006e31c6eb08