perf record: Move mmap setup block to separate function

Following commits introduce multiple evlists to record. This patch
extracts perf_evlist__mmap_ex() processing to a new function, creates
record__mmap() and record__mmap_evlist() to wrap perf_evlist__mmap_ex()
and its error processing. They will be improvemented to create mmap for
all evlists.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1467023052-146749-2-git-send-email-wangnan0@huawei.com


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