ftrace_reader: Add new ftrace events

Plumb events for atrace categories freq, load and idle.

Change-Id: I5f2ad525647d6b5fe779b572dc82c75345e500b4
diff --git a/tools/pull_ftrace_format_files.py b/tools/pull_ftrace_format_files.py
index de5d3a7..abf27ac 100755
--- a/tools/pull_ftrace_format_files.py
+++ b/tools/pull_ftrace_format_files.py
@@ -93,6 +93,7 @@
       "-name format -o " \
       "-name header_event -o " \
       "-name header_page | " \
+      "grep -v '/instances/' | " \
       "while read f; do echo 'path:' $f; cat $f; done"
 
   output = adb('shell', cmd, serial=serial)