plat/arm: css: Turn ON/OFF redistributor in sync with GIC CPU interface ON/OFF

Turn ON/OFF GIC redistributor in sync with GIC CPU interface ON/OFF.

Issue :
The Linux prompt hangs when all the cores in a cluster are turned OFF
and we try to turn ON a core in that cluster. Previously when TF-A turns
ON a core, TF-A first turns ON the redistributor followed by the core.
This did not match the flow when turning OFF a core, as TF-A did not
turn OFF redistributor when the corresponding core[s] are disabled.
This hang is resolved by disabling redistributor as cores are disabled,
keeping them in sync.

Signed-off-by: Jagadeesh Ujja <jagadeesh.ujja@arm.com>
Change-Id: Ifd04fdcfd47b45e00f874f15b098471883d023f0

plat/arm/css/common/css_pm.c

@@ -123,6 +123,9 @@ static void css_power_down_common(const psci_power_state_t *target_state)
 	/* Prevent interrupts from spuriously waking up this cpu */
 	plat_arm_gic_cpuif_disable();
 
+	/* Turn redistributor off */
+	plat_arm_gic_redistif_off();
+
 	/* Cluster is to be turned off, so disable coherency */
 	if (CSS_CLUSTER_PWR_STATE(target_state) == ARM_LOCAL_STATE_OFF) {
 		plat_arm_interconnect_exit_coherency();