perf dlfilter: Drop unused variable

Compiling tools/perf/dlfilters/dlfilter-test-api-v0.c result in:

	checking for stdlib.h... dlfilters/dlfilter-test-api-v0.c: In function ‘filter_event’:
	dlfilters/dlfilter-test-api-v0.c:311:29: warning: unused variable ‘d’ [-Wunused-variable]
	  311 |         struct filter_data *d = data;
	      |

So remove the  variable now.
Reviewed-by: German Gomez <german.gomez@arm.com>
Signed-off-by: Salvatore Bonaccorso <carnil@debian.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20211123211821.132924-1-carnil@debian.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/dlfilters/dlfilter-test-api-v0.c

@@ -308,8 +308,6 @@ int filter_event_early(void *data, const struct perf_dlfilter_sample *sample, vo
 
 int filter_event(void *data, const struct perf_dlfilter_sample *sample, void *ctx)
 {
-	struct filter_data *d = data;
-
 	pr_debug("%s API\n", __func__);
 
 	return do_checks(data, sample, ctx, false);