perf c2c: Use 'peer' as default display for Arm64

Since Arm64 arch doesn't support HITMs flags, this patch changes to use
'peer' as default display if user doesn't specify any type; for other
arches, it still uses 'tot' as default display type if user doesn't
specify it.

This patch changes to call perf_session__new() in an earlier place, so
session environment can be initialized ahead and arch info can be used
for setting display type.

Suggested-by: Ali Saidi <alisaidi@amazon.com>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Acked-by: Ian Rogers <irogers@google.com>
Tested-by: Ali Saidi <alisaidi@amazon.com>
Reviewed-by: Ali Saidi <alisaidi@amazon.com>