arm-cci: fix handling cpumask_any_but return value

cpumask_any_but returns value >= nr_cpu_ids if there are no more CPUs.

The problem has been detected using proposed semantic patch
scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci [1].

[1]: http://permalink.gmane.org/gmane.linux.kernel/2038576



Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>