perf config: Refactor the code using 'ret' variable in cmd_config()

To simplify the code related to 'ret' variable in cmd_config(),
initialize 'ret' with -1 instead of 0 and use goto to perform resource
release at the end of the function, setting ret to zero just before the
out_err label, as usual in the kernel sources.

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1497671202-20495-1-git-send-email-treeze.taeung@gmail.com


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