Disable KM4 HMAC key agreement

StrongBox doesn't yet have key agreement implemented, which breaks
keystore if TEE KM is upgraded to KM4.  This disables it temporarily.

Bug: 77533310
Test: Boot and verify that keystore is running correctly.
Change-Id: I8505f634735d1efc5a196fdfd0910b1b26da7547
diff --git a/keystore/keystore_main.cpp b/keystore/keystore_main.cpp
index 1ec32dd..58f0733 100644
--- a/keystore/keystore_main.cpp
+++ b/keystore/keystore_main.cpp
@@ -122,9 +122,8 @@
         CHECK(rc.isOk()) << "Communication error while calling getHmacSharingParameters on"
                             " Keymaster with index: "
                          << index;
-        CHECK(ec == ErrorCode::OK) << "Failed to get HmacSharingParameters from"
-                                      " Keymaster with index: "
-                                   << index;
+        CHECK(ec == ErrorCode::OK) << "Failed to get HmacSharingParameters from Keymaster "
+                                   << km->halVersion().keymasterName << " at index: " << index;
         ++index;
     }
     hmacSharingParams.resize(index);
@@ -160,8 +159,9 @@
     auto result = enumerateKeymasterDevices<Keymaster4>(serviceManager.get());
     auto softKeymaster = result[SecurityLevel::SOFTWARE];
     if (result[SecurityLevel::TRUSTED_ENVIRONMENT]) {
-        performHmacKeyHandshake(
-            {result[SecurityLevel::TRUSTED_ENVIRONMENT], result[SecurityLevel::STRONGBOX]});
+        // TODO(swillden): Put this back when StrongBox KM works. b/77533310
+        // performHmacKeyHandshake(
+        //     {result[SecurityLevel::TRUSTED_ENVIRONMENT], result[SecurityLevel::STRONGBOX]});
     } else {
         result = enumerateKeymasterDevices<Keymaster3>(serviceManager.get());
     }