Playback/Capture can't work on UP^2

[ZhendanYang]

Summary:
After booting, there was no error message in dmesg. Then I tried to playback/capture, but playback/capture couldn't work and ipc error occurred.

Environment:
on up^2 with gcc
sof-dev:7481f7af7ac711504ae52fa9ae5cb5c3322ea91f
sof:4aff776d1c290542ded98f8aa22f50d4b9477d37
soft:41861aac373eb1f6978bfdb0bbe97cd882b1785a
tplg:sof-apl-nocodec.tplg
(I tested on sof-dev : c465461 and there was no such issue)

Log:
dmesg-up2.log
rmbox-t-up2.log
rmbox-up2.log

[ghost]

@lgirdwood
I added test code like this below in the function sof_route_load()

	sroute->route.source = kstrdup(route->source, GFP_KERNEL);
	if (!sroute->route.source) {
		dev_err(sdev->dev, "==wzg: route soure malloc fail %s\n",sroute->route.source);
		goto err;
	}

	sroute->route.sink = kstrdup(route->sink, GFP_KERNEL);
	if (!sroute->route.sink) {
		dev_err(sdev->dev, "==wzg: route sink malloc fail %s\n",sroute->route.source);
		kfree(sroute->route.source);
		goto err;
	}

	sroute->route.control = kstrdup(route->control, GFP_KERNEL);
	if (!sroute->route.control) {
		dev_err(sdev->dev, "==wzg: route control malloc fail %s\n",sroute->route.source);
		kfree(sroute->route.source);
		kfree(sroute->route.sink);
		goto err;
	}

I got the log: "route control malloc fail .....".
It is strange. I do not know why this would happen.
It seems it failed many times.

[ghost]

@lgirdwood
I found the root cause of this PR #80
I will send another fix for this issue.

[ghost]

@lgirdwood
The root cause is: the upper function will sometimes set the route->control pointer = NULL.
then in the sof_route_load() function, it will malloc failure. the error will happen. the route is not added
into the list. the IPC error will happen.

[ghost]

fixed by the PR #99