By writing 0 to CLUSTERPWRDN DSU register bit 0, we send an
advisory to the power controller that cluster power is not required
when all cores are powered down.
The AArch32 CLUSTERPWRDN register is architecturally mapped to the
AArch64 CLUSTERPWRDN_EL1 register
Change-Id: Ie6e67c1c7d811fa25c51e2e405ca7f59bd20c81b
Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>