config-linux: Add restriction for duplicated device path

I think runtime should generate an error, if devices has
duplicated device path.
Because we don't know which one is really needed.

Signed-off-by: Ma Shimiao <[email protected]>

Author: Ma Shimiao

config-linux.md

@@ -121,6 +121,9 @@ Each entry has the following structure:
 * **`uid`** *(uint32, OPTIONAL)* - id of device owner.
 * **`gid`** *(uint32, OPTIONAL)* - id of device group.
 
+If a `devices` contains duplicated devices with same `path`, the runtime MUST generate an error.
+Duplicated devices with same `major, minor` is acceptable, but it is not recommended.
+
 ###### Example
 
 ```json