perf top: Do show usage message when failing to create cpu/thread maps

This is necessary to get rid of the browser dependency from
usage_with_options() and its friends.  Because we validate the targets
which are used to create the cpu/thread maps and inform the user about
any override performed via the chosen UI, we don't need to call the
usage routine for that.

Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-slu7lj7buzpwgop1vo9la8ma@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>