tpm: vtpm_proxy: Suppress error logging when in closed state

Suppress the error logging when the core TPM driver sends commands
to the VTPM proxy driver and -EPIPE is returned in case the VTPM
proxy driver is 'closed' (closed anonymous file descriptor).  This
error code is only returned by the send function and by tpm_transmit
when the VTPM proxy driver is being used.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Tested-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index 3ee6883..3a99643 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -840,7 +840,7 @@
 	/* In places where shutdown command is sent there's no much we can do
 	 * except print the error code on a system failure.
 	 */
-	if (rc < 0)
+	if (rc < 0 && rc != -EPIPE)
 		dev_warn(&chip->dev, "transmit returned %d while stopping the TPM",
 			 rc);
 }