perf synthetic-events: Avoid unnecessary memset

perf synthetic-events: Avoid unnecessary memset

Make sure the memset of a synthesized event only zeros the necessary
tracing data part of the event, as a full event can be over 4kb in
size.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Anne Macedo <retpolanne@posteo.net>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Casey Chen <cachen@purestorage.com>
Cc: Chaitanya S Prakash <chaitanyas.prakash@arm.com>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Dominique Martinet <asmadeus@codewreck.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jann Horn <jannh@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sun Haiyong <sunhaiyong@loongson.cn>
Cc: Weilin Wang <weilin.wang@intel.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Yunseong Kim <yskelg@gmail.com>
Cc: Ze Gao <zegao2021@gmail.com>
Link: https://lore.kernel.org/r/20240817064442.2152089-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>