Update version in backuptool.functions too

Change-Id: Idbdf7ffbec037a78c2d3df4ca2a83c1058c19279
diff --git a/prebuilt/common/bin/backuptool.functions b/prebuilt/common/bin/backuptool.functions
index ef8479a..90943b3 100644
--- a/prebuilt/common/bin/backuptool.functions
+++ b/prebuilt/common/bin/backuptool.functions
@@ -5,7 +5,7 @@
 
 export C=/tmp/backupdir
 export S=/system
-export V=10.1
+export V=10.2
 
 backup_file() {
   if [ -e "$1" ]; then