perf trace: Guard __probe_ip suppression with evsel__is_probe()

perf trace: Guard __probe_ip suppression with evsel__is_probe()

trace__fprintf_tp_fields() compares every field name against
"__probe_ip" for all tracepoint events, but this field is only
implicitly added by the Ftrace subsystem to bare dynamic probes.

Add an evsel__is_probe() check before the strcmp so the string
comparison is skipped entirely for non-probe events.

Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>