Make RKPD default

Also, remove usage of
"persist.device_config.remote_key_provisioning_native.enable_rkpd".

Test: keystore2_test
Change-Id: I3e6673f1af45adf7f7075e61523621ac9377f414
diff --git a/identity/CredentialStore.cpp b/identity/CredentialStore.cpp
index fea4df9..e2b3cf4 100644
--- a/identity/CredentialStore.cpp
+++ b/identity/CredentialStore.cpp
@@ -47,7 +47,7 @@
 
 bool useRkpd() {
     return android::base::GetBoolProperty("remote_provisioning.enable_rkpd",
-                                          /*default_value=*/false);
+                                          /*default_value=*/true);
 }
 
 }  // namespace