opal/hmi: Rework HMI handling of TFAC errors

This patch reworks the HMI handling for TFAC errors by introducing
4 rendez-vous points improve the thread synchronization while handling
timebase errors that requires all thread to clear dirty data from TB/HDEC
register before clearing the errors.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.ibm.com>

core/cpu.c

@@ -1107,7 +1107,6 @@ void init_all_cpus(void)
 #endif
 		t->core_hmi_state = 0;
 		t->core_hmi_state_ptr = &t->core_hmi_state;
-		t->thread_mask = 1;
 
 		/* Add associativity properties */
 		add_core_associativity(t);
@@ -1131,7 +1130,6 @@ void init_all_cpus(void)
 			t->node = cpu;
 			t->chip_id = chip_id;
 			t->core_hmi_state_ptr = &pt->core_hmi_state;
-			t->thread_mask = 1 << thread;
 		}
 		prlog(PR_INFO, "CPU:  %d secondary threads\n", thread);
 	}