vendor: fix backup versions

Change-Id: Ifcaea3075ffe43737d7688fd74448cc019928975
diff --git a/prebuilt/common/bin/backuptool_ab.functions b/prebuilt/common/bin/backuptool_ab.functions
index f227ec1..a4d1ada 100644
--- a/prebuilt/common/bin/backuptool_ab.functions
+++ b/prebuilt/common/bin/backuptool_ab.functions
@@ -5,7 +5,7 @@
 
 export S=/system
 export C=/postinstall/tmp/backupdir
-export V=9.0
+export V=9
 export backuptool_ab=true
 
 copy_file() {