dt-bindings: net: dsa: hellcreek: Sync DSA maintainers

The current DSA maintainers are Florian Fainelli, Andrew Lunn and Vladimir
Oltean. Update the hellcreek binding accordingly.
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20221212081546.6916-1-kurt@linutronix.deSigned-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/dsa/hirschmann,hellcreek.yaml

@@ -12,7 +12,7 @@ allOf:
 maintainers:
   - Andrew Lunn <andrew@lunn.ch>
   - Florian Fainelli <f.fainelli@gmail.com>
-  - Vivien Didelot <vivien.didelot@gmail.com>
+  - Vladimir Oltean <olteanv@gmail.com>
   - Kurt Kanzenbach <kurt@linutronix.de>
 
 description: