perf script: Remove duplicated code and needless script_spec__findnew()

perf script: Remove duplicated code and needless script_spec__findnew()

script_spec_register() called two functions: script_spec__find() and
script_spec__findnew().  But this way script_spec__find() gets called
two times, directly and via script_spec__findnew().

So remove script_spec__findnew() and make script_spec_register() only
call once script_spec__find().

Signed-off-by: Taeung Song <treeze.taeung@gmail.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/1456413190-12378-1-git-send-email-treeze.taeung@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>