[IA64] Re-implement spinaphores using ticket lock concepts

Bound the wait time for the ptcg_sem by using similar idea to the
ticket spin locks.  In this case we have only one instance of a
spinaphore, so make it 8 bytes rather than try to squeeze it into
4-bytes to keep the code simpler (and shorter).

Signed-off-by: Tony Luck <tony.luck@intel.com>