perf top: Use callchain_param.enabled instead of symbol_conf.use_callchain

perf top: Use callchain_param.enabled instead of symbol_conf.use_callchain

One more step in the direction of using just callchain_param for
callchain parameters.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-3b1o9kb2dc94zldz0klckti6@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>