[KM-VM] Add rollback index to KM VM AVB footer

Bug: 369299899
Test: launch_cvd --secure_hals=guest_keymint_trusty_insecure
Change-Id: Ic48886914de955d142da5732b602a25861e18f68
diff --git a/guest/trusty/security_vm/launcher/Android.bp b/guest/trusty/security_vm/launcher/Android.bp
index e482e02..ef32740 100644
--- a/guest/trusty/security_vm/launcher/Android.bp
+++ b/guest/trusty/security_vm/launcher/Android.bp
@@ -40,12 +40,15 @@
 // python -c "import hashlib; print(hashlib.sha256(b'trusty_security_vm_salt').hexdigest())"
 trusty_security_vm_salt = "75a71e967c1a1e0f805cca20465e7acf83e6a04e567a67c426d8b5a94f8d61c5"
 
+TRUSTY_SECURITY_VM_VERSION = 1
+
 avb_add_hash_footer {
     name: "trusty_security_vm_signed",
     filename: "trusty_security_vm_signed",
     partition_name: "boot",
     private_key: ":trusty_vm_sign_key",
     salt: trusty_security_vm_salt,
+    rollback_index: TRUSTY_SECURITY_VM_VERSION,
     src: ":empty_file",
     enabled: false,
     arch: {