c/layer.conf: Pin homescreen revision

Fix observed issue:

```
  homescreen[285]: libc++abi: \
  terminating with uncaught exception of type std::invalid_argument: \
  stol: no conversion

```

To be fixed once linux plugin intergrated and systemd services
adjusted

Relate-to: #3


Signed-off-by: Philippe Coval <philippe.coval.ext@huawei.com>