Update VTS tag version to v8.1_R8

Test:mma
Bug:119873069
Change-Id: Id369ad78bef2cd6662bd55e9104dde5738039ae5
diff --git a/tools/vts-tradefed/Android.mk b/tools/vts-tradefed/Android.mk
index 5661e9a..d33d423 100644
--- a/tools/vts-tradefed/Android.mk
+++ b/tools/vts-tradefed/Android.mk
@@ -24,7 +24,7 @@
 LOCAL_SUITE_TARGET_ARCH := $(TARGET_ARCH)
 LOCAL_SUITE_NAME := VTS
 LOCAL_SUITE_FULLNAME := "Vendor Test Suite"
-LOCAL_SUITE_VERSION := 8.1_R7
+LOCAL_SUITE_VERSION := 8.1_R8
 LOCAL_STATIC_JAVA_LIBRARIES := \
     libvts_protos_host \