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

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