perf annotate: Get rid of annotation->nr_jumps

perf annotate: Get rid of annotation->nr_jumps

The 'nr_jumps' field in 'struct annotation' is not used since it's
inception in commit c46d58e5e0ab ("perf annotate browser: Show 'jumpy'
functions").  Get rid of it.

Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Link: http://lore.kernel.org/lkml/20200204045233.474937-7-ravi.bangoria@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>