simpleperf: fix dumping symbols for unwinded ips.

Previous code dumps symbols for unwinded ips regardless of
--dump-symbols option. Fix it to be controled by --dump-symbols
option.

Bug: 29581559
Change-Id: Ie7a79bf5275c13b0df4352e4aedc702f34b7b899
Test: run simpleperf_unit_test.
2 files changed