update bootloader to 3.39

 1. Fix problems of TI PMIC
 2. Set boot-up reason
 3. Avoid condition that device can't be powered on by AC/USB

Change-Id: I5c8ef2311be925adac7ef57f19cfb41e3912a3ed
diff --git a/board-info.txt b/board-info.txt
index 4390af6..0f19e55 100644
--- a/board-info.txt
+++ b/board-info.txt
@@ -1,2 +1,2 @@
 require board=grouper
-require version-bootloader=3.38
+require version-bootloader=3.39