perf c2c: Update documentation for display option 'all'

maillist inclusion
category: Feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I53L83
CVE: NA

Reference: https://lore.kernel.org/all/20210104020930.GA4897@leoy-ThinkPad-X240s/



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Since the new display option 'all' is introduced, this patch is to
update the documentation to reflect it.

Signed-off-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Reviewed-by: Wei Li <liwei391@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>