perf docs: Update metric usage for Alibaba's T-Head PMU driver (arm64)

Alibaba's T-Head ali_drw PMU supports DDR bandwidth metrics. Update
its usage in the documentation.

Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Jing Zhang <renyu.zj@linux.alibaba.com>
Acked-by: Ian Rogers <irogers@google.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Shuai Xue <xueshuai@linux.alibaba.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zhuo Song <zhuo.song@linux.alibaba.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-doc@vger.kernel.org
Link: https://lore.kernel.org/r/1690528175-2499-4-git-send-email-renyu.zj@linux.alibaba.com


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>