Use common macro PMU_EVENT_ATTR_ID to simplify L3CACHE_EVENT_ATTR

Cc: Andy Gross <agross@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Qi Liu <liuqi115@huawei.com>
Link: https://lore.kernel.org/r/1623220863-58233-5-git-send-email-liuqi115@huawei.comSigned-off-by: Will Deacon <will@kernel.org>