Add mm_event trace events to the atrace 'memory' category

Bug: 150130660
Test: Recorded a trace via the atrace commandline and verified
mm_event entries were included.

Change-Id: I5f7f7571496c31c77210fa0673829dc6c6223ac7
diff --git a/cmds/atrace/atrace.cpp b/cmds/atrace/atrace.cpp
index 544e26c..8637a31 100644
--- a/cmds/atrace/atrace.cpp
+++ b/cmds/atrace/atrace.cpp
@@ -233,6 +233,7 @@
         { REQ,      "events/filemap/enable" },
     } },
     { "memory",  "Memory", 0, {
+        { OPT,      "events/mm_event/mm_event_record/enable" },
         { OPT,      "events/kmem/rss_stat/enable" },
         { OPT,      "events/kmem/ion_heap_grow/enable" },
         { OPT,      "events/kmem/ion_heap_shrink/enable" },