schema/defs-linux.json: fix max for FileMode

Current spec allows decimal 512 as a maximum value for FileMode,
which is octal 1000, meaning sticky bit is set and no rwx permissions
for anyone (aka s---------).

This does not make sense,the maximum value should be 511 (which is
octal 777, aka -rwxrwxrwx).

Signed-off-by: Kir Kolyshkin <[email protected]>

Author: kolyshkin

schema/defs-linux.json

@@ -152,7 +152,7 @@
             "description": "File permissions mode (in decimal, not octal)",
             "type": "integer",
             "minimum": 0,
-            "maximum": 512
+            "maximum": 511
         },
         "FileType": {
             "description": "Type of a block or special character device",