perf scripts python: exported-sql-viewer.py: Fix time chart call tree

Using Python version 3.8.2 and PySide2 version 5.14.0, time chart call tree
would not expand the tree to the result. Fix by using setExpanded().

Example:

  $ perf record -e intel_pt//u uname
  Linux
  [ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.034 MB perf.data ]
  $ perf script --itrace=bep -s ~/libexec/perf-core/scripts/python/export-to-sqlite.py perf.data.db branches calls
  2020-06-26 15:32:14.928997 Creating database ...
  2020-06-26 15:32:14.933971 Writing records...
  2020-06-26 15:32:15.535251 Adding indexes
  2020-06-26 15:32:15.542993 Dropping unused tables
  2020-06-26 15:32:15.549716 Done
  $ python3 ~/libexec/perf-core/scripts/python/exported-sql-viewer.py perf.data.db

  Select: Charts -> Time chart by CPU
  Move mouse over middle of chart
  Right-click and select Show Call Tree

Before: displays Call Tree but not expanded to selected time
After: displays Call Tree expanded to selected time

Fixes: e69d5df7 ("perf scripts python: exported-sql-viewer.py: Add ability for Call tree to open at a specified task and time")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lore.kernel.org/lkml/20200629091955.17090-7-adrian.hunter@intel.com


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