dt-bindings: net: tsnep: Fix typo on generic nvmem property

While working on the nvmem description I figured out this file had the
"nvmem-cell-names" property name misspelled. Fix the typo, as
"nvmem-cells-names" has never existed.

Fixes: 603094b ("dt-bindings: net: Add tsnep Ethernet controller")
Signed-off-by: Miquel Raynal <[email protected]>
Reviewed-by: Gerhard Engleder <[email protected]>
Acked-by: Rob Herring <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Documentation/devicetree/bindings/net/engleder,tsnep.yaml

@@ -47,7 +47,7 @@ properties:
 
   nvmem-cells: true
 
-  nvmem-cells-names: true
+  nvmem-cell-names: true
 
   phy-connection-type:
     enum: