dt-bindings: ARM: at91: update maintainers entry

Align the binding documentation with the newly updated MAINTAINERS
entry.

Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Acked-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Link: https://lore.kernel.org/r/5bf9873eeee3cd49c52a8952a7cd4cb60b61d50a.1643553501.git.nicolas.ferre@microchip.com

Documentation/devicetree/bindings/arm/atmel-at91.yaml

@@ -8,7 +8,8 @@ title: Atmel AT91 device tree bindings.
 
 maintainers:
   - Alexandre Belloni <alexandre.belloni@bootlin.com>
-  - Ludovic Desroches <ludovic.desroches@microchip.com>
+  - Claudiu Beznea <claudiu.beznea@microchip.com>
+  - Nicolas Ferre <nicolas.ferre@microchip.com>
 
 description: |
   Boards with a SoC of the Atmel AT91 or SMART family shall have the following