[IA64] Rename TIF_PERFMON_WORK back to TIF_NOTIFY_RESUME

Since the RSE synchronization will need a TIF_ flag, but all

work-to-be-done bits are already used, so we have to multiplex
TIF_NOTIFY_RESUME again.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Petr Tesarik <ptesarik@suse.cz>
Signed-off-by: Tony Luck <tony.luck@intel.com>