networkd: Add ENOENT to the list of expected errors in Sysfs.read_one_line

Otherwise this quite frequently logs something like:

```
xcp-networkd: [error||22 |dbsync (update_env)|network_utils]
Error in read one line of file: /sys/class/net/eth0/device/sriov_totalvfs,
exception Unix.Unix_error(Unix.ENOENT, "open", "/sys/class/net/eth0/device/sriov_totalvfs")
Backtrace ...
```

Signed-off-by: Andrii Sultanov <[email protected]>

Author: last-genius

ocaml/networkd/lib/network_utils.ml

@@ -162,7 +162,8 @@ module Sysfs = struct
     with
     | End_of_file ->
         ""
-    | Unix.Unix_error (Unix.EINVAL, _, _) ->
+    | Unix.Unix_error (Unix.EINVAL, _, _) | Unix.Unix_error (Unix.ENOENT, _, _)
+      ->
         (* The device is not yet up *)
         raise (Network_error (Read_error file))
     | exn ->