perf mem-events: Remove unnecessary 'struct mem_info' forward declaration

'struct mem_info' is defined at 22nd line.

The declaration here is unnecessary. Remove it.
Signed-off-by: NWan Jiabing <wanjiabing@vivo.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: kael_w@yeah.net
Link: http://lore.kernel.org/lkml/20210406105104.675879-1-wanjiabing@vivo.comSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/mem-events.h

@@ -44,7 +44,6 @@ bool is_mem_loads_aux_event(struct evsel *leader);
 
 void perf_mem_events__list(void);
 
-struct mem_info;
 int perf_mem__tlb_scnprintf(char *out, size_t sz, struct mem_info *mem_info);
 int perf_mem__lvl_scnprintf(char *out, size_t sz, struct mem_info *mem_info);
 int perf_mem__snp_scnprintf(char *out, size_t sz, struct mem_info *mem_info);