perf: arm_dsu: Support DSU ACPI devices

Add support for probing device from ACPI node.
Each DSU ACPI node and its associated cpus are inside a cluster node.

Signed-off-by: Tuan Phan <tuanphan@os.amperecomputing.com>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/1600106656-9542-1-git-send-email-tuanphan@os.amperecomputing.com
Signed-off-by: Will Deacon <will@kernel.org>