staging: unisys: visorbus: add error handling to remaining_steps_show

Don't just drop the error from visorchannel_read on the floor, report it.
Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Reviewed-by: Tim Sell <timothy.sell@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/unisys/visorbus/visorchipset.c

@@ -242,11 +242,15 @@ static ssize_t remaining_steps_show(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
 	u16 remaining_steps = 0;
+	int err;
 
-	visorchannel_read(chipset_dev->controlvm_channel,
+	err = visorchannel_read(chipset_dev->controlvm_channel,
 				offsetof(struct spar_controlvm_channel_protocol,
 					 installation_remaining_steps),
 				&remaining_steps, sizeof(u16));
+	if (err)
+		return err;
+
 	return sprintf(buf, "%hu\n", remaining_steps);
 }