perf: hisi: Extract hisi_pmu_init

Extract the initialization code of hisi_pmu->pmu into a function

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Link: https://lore.kernel.org/r/20220516131601.48383-1-chenjun102@huawei.com


Signed-off-by: Will Deacon <will@kernel.org>