Refactor function signatures to remove mocked IRPC

Test: atest libkeymint_remote_prov_support_test
      atest VtsHalRemotelyProvisionedComponentTargetTest

Change-Id: I8dd47bca149bcef244c223f8e94d3965deb13f13
diff --git a/security/keymint/support/Android.bp b/security/keymint/support/Android.bp
index f313cf3..271e36c 100644
--- a/security/keymint/support/Android.bp
+++ b/security/keymint/support/Android.bp
@@ -114,6 +114,7 @@
 
 cc_test {
     name: "libkeymint_remote_prov_support_test",
+    cpp_std: "c++20",
     srcs: ["remote_prov_utils_test.cpp"],
     static_libs: [
         "android.hardware.security.rkp-V3-ndk",