libperf: Move 'nr_mmaps' from 'struct evlist' to 'struct perf_evlist'

Moving 'nr_mmaps' from 'struct evlist' to 'struct perf_evlist', it will
be used in following patches.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lore.kernel.org/lkml/20190913132355.21634-21-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/arch/x86/tests/perf-time-to-tsc.c

@@ -115,7 +115,7 @@ int test__perf_time_to_tsc(struct test *test __maybe_unused, int subtest __maybe
 
 	evlist__disable(evlist);
 
-	for (i = 0; i < evlist->nr_mmaps; i++) {
+	for (i = 0; i < evlist->core.nr_mmaps; i++) {
 		md = &evlist->mmap[i];
 		if (perf_mmap__read_init(md) < 0)
 			continue;