usb: typec: intel_pmc_mux: Handle SCU IPC error conditions

Check and return if there are errors. The response bits are valid
only on no errors.

Fixes: b7404a29 ("usb: typec: intel_pmc_mux: Definitions for response status bits")
Signed-off-by: Madhusudanarao Amara <madhusudanarao.amara@intel.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20200916091102.27118-4-heikki.krogerus@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/mux/intel_pmc_mux.c

@@ -125,13 +125,19 @@ static int hsl_orientation(struct pmc_usb_port *port)
 static int pmc_usb_command(struct pmc_usb_port *port, u8 *msg, u32 len)
 {
 	u8 response[4];
+	int ret;
 
 	/*
 	 * Error bit will always be 0 with the USBC command.
-	 * Status can be checked from the response message.
+	 * Status can be checked from the response message if the
+	 * function intel_scu_ipc_dev_command succeeds.
 	 */
-	intel_scu_ipc_dev_command(port->pmc->ipc, PMC_USBC_CMD, 0, msg, len,
-				  response, sizeof(response));
+	ret = intel_scu_ipc_dev_command(port->pmc->ipc, PMC_USBC_CMD, 0, msg,
+					len, response, sizeof(response));
+
+	if (ret)
+		return ret;
+
 	if (response[2] & PMC_USB_RESP_STATUS_FAILURE) {
 		if (response[2] & PMC_USB_RESP_STATUS_FATAL)
 			return -EIO;