perf scripts python: call-graph-from-sql.py: Change icon

There are not many standard icons, but the computer icon looks slightly
better than the information icon.

Committer testing:

Noticed the change on the icon on the gnome menu right next to the
"Activities" menu, looks nicer indeed.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20181001062853.28285-5-adrian.hunter@intel.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/scripts/python/call-graph-from-sql.py

@@ -271,9 +271,7 @@ class MainWindow(QMainWindow):
 		self.setWindowTitle("Call Graph: " + dbname)
 		self.move(100, 100)
 		self.resize(800, 600)
-		style = self.style()
-		icon = style.standardIcon(QStyle.SP_MessageBoxInformation)
-		self.setWindowIcon(icon);
+		self.setWindowIcon(self.style().standardIcon(QStyle.SP_ComputerIcon))
 		self.setMinimumSize(200, 100)
 
 		self.model = TreeModel(db)