tpm_manager: Use owner_password when locking nvram

This CL changes the authorization forwarded to LockNvram from "" to
owner_password.
BUG=None
TEST=nvram tests on DUT

Change-Id: Idf4efc6096496d1ad5e1d9ff31739d9c63b38243
diff --git a/server/tpm2_nvram_impl.cc b/server/tpm2_nvram_impl.cc
index e9cee57..d06bc87 100644
--- a/server/tpm2_nvram_impl.cc
+++ b/server/tpm2_nvram_impl.cc
@@ -118,7 +118,6 @@
     LOG(ERROR) << "Error writing to nvram space: " << GetErrorString(result);
     return false;
   }
-  trunks_session_->SetEntityAuthorizationValue("");
   result = trunks_utility_->LockNVSpace(index, trunks_session_->GetDelegate());
   if (result != TPM_RC_SUCCESS) {
     LOG(ERROR) << "Error locking nvram space: " << GetErrorString(result);