perf report: Remove duplicated 'samples' in lost samples warning

The following message, emitted when samples are lost due to system
overload, had one 'samples' too many, ditch it:

   Processed 25333 samples and lost 20.88% samples!

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Kan Liang <kan.liang@intel.com>
Link: https://lkml.kernel.org/n/tip-oev1469y02hmfere6r2kkxp6@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>