Revert "Remove incorrect return value read"

This reverts commit 1ed701682aab38fc77118f5d44dc4c73be5f2807.

Change-Id: Ib5cfb053accd198f2a5c0d5f8a6f0c8e046a15a8
diff --git a/keystore/IKeystoreService.cpp b/keystore/IKeystoreService.cpp
index 79edd42..b4e35ab 100644
--- a/keystore/IKeystoreService.cpp
+++ b/keystore/IKeystoreService.cpp
@@ -1077,6 +1077,7 @@
             return;
         }
         int32_t err = reply.readExceptionCode();
+        int32_t ret = reply.readInt32();
         if (err < 0) {
             ALOGD("exportKey() caught exception %d\n", err);
             result->resultCode = KM_ERROR_UNKNOWN_ERROR;