attestation: add missing log

If the caller ends up to fail, the added log is helpful with diagnosis.

BUG=b:146525460
TEST=build ok.

Change-Id: Ifa1fbda766409e3078101612e17b64ad552a37ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2603675
Tested-by: Leo Lai <cylai@google.com>
Commit-Queue: Leo Lai <cylai@google.com>
Reviewed-by: Yi Chou <yich@google.com>
diff --git a/attestation/common/tpm_utility_v2.cc b/attestation/common/tpm_utility_v2.cc
index 604d482..f9aaf1c 100644
--- a/attestation/common/tpm_utility_v2.cc
+++ b/attestation/common/tpm_utility_v2.cc
@@ -108,6 +108,8 @@
 crypto::ScopedEC_KEY GetEccPublicKeyFromTpmPublicArea(
     const trunks::TPMT_PUBLIC& public_area) {
   if (public_area.type != trunks::TPM_ALG_ECC) {
+    LOG(ERROR) << __func__
+               << ": Unexpected algorithm type: " << public_area.type;
     return nullptr;
   }