arm64: dts: hip05: Use Cortex specific device node for pmu

Instead of using the generic armv8-pmuv3 compatibility, use
the more specific Cortex A57 compatibility.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>