perf trace: Switch to using a struct for the aumented_raw_syscalls syscalls map values

We'll start adding more perf-syscall stuff, so lets do this prep step so
that the next ones are just about adding more fields.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-vac4sn1ns1vj4y07lzj7y4b8@git.kernel.org


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