tracing/hist: Fix wrong return value in parse_action_params()

When number of synth fields is more than SYNTH_FIELDS_MAX,
parse_action_params() should return -EINVAL.

Link: https://lore.kernel.org/linux-trace-kernel/20221207034635.2253990-1-zhengyejian1@huawei.com



Cc: <mhiramat@kernel.org>
Cc: <zanussi@kernel.org>
Cc: stable@vger.kernel.org
Fixes: c282a386 ("tracing: Add 'onmatch' hist trigger action support")
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>