tpm: Don't cleanup unless an error happens

At present the cleanup() method is called on every transfer. It should
only be called on failing transfers. Fix this and tidy up the error
handling a little.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/drivers/tpm/tpm-uclass.c b/drivers/tpm/tpm-uclass.c
index 1b11c93..71d5807 100644
--- a/drivers/tpm/tpm-uclass.c
+++ b/drivers/tpm/tpm-uclass.c
@@ -72,7 +72,7 @@
 	struct tpm_ops *ops = tpm_get_ops(dev);
 	ulong start, stop;
 	uint count, ordinal;
-	int ret, ret2;
+	int ret, ret2 = 0;
 
 	if (ops->xfer)
 		return ops->xfer(dev, sendbuf, send_size, recvbuf, recv_size);
@@ -120,9 +120,16 @@
 		}
 	} while (ret);
 
-	ret2 = ops->cleanup ? ops->cleanup(dev) : 0;
+	if (ret) {
+		if (ops->cleanup) {
+			ret2 = ops->cleanup(dev);
+			if (ret2)
+				return log_msg_ret("cleanup", ret2);
+		}
+		return log_msg_ret("xfer", ret);
+	}
 
-	return ret2 ? ret2 : ret;
+	return 0;
 }
 
 UCLASS_DRIVER(tpm) = {