Depend on KeyMint HAL via default

This allows for easier bumping of the KeyMint version level.

At the moment this change should have no effect: the same dependency
is used, just reached via a default rather than explicitly.

However, when the KeyMint version increases in the near future, using
this default should mean that no change is needed here: the default
definition will change to -V2 and this will be referenced here.

Test: TreeHugger
Change-Id: I8cce78e7f56179db23b2de792764ea2cae2d3cb7
diff --git a/keystore2/Android.bp b/keystore2/Android.bp
index 60326da..3097bae 100644
--- a/keystore2/Android.bp
+++ b/keystore2/Android.bp
@@ -25,9 +25,11 @@
     name: "libkeystore2_defaults",
     crate_name: "keystore2",
     srcs: ["src/lib.rs"],
+    defaults: [
+        "keymint_use_latest_hal_aidl_rust",
+    ],
 
     rustlibs: [
-        "android.hardware.security.keymint-V1-rust",
         "android.hardware.security.secureclock-V1-rust",
         "android.hardware.security.sharedsecret-V1-rust",
         "android.os.permissions_aidl-rust",