dt-bindings: net: can: add "st,can-secondary" property

On the stm32f7 Socs the can peripheral can be in single or dual
configuration. In the dual configuration, in turn, it can be in primary
or secondary mode. The addition of the 'st,can-secondary' property allows
you to specify this mode in the dual configuration.

CAN peripheral nodes in single configuration contain neither
"st,can-primary" nor "st,can-secondary".
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/all/20230427204540.3126234-2-dario.binacchi@amarulasolutions.comSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Documentation/devicetree/bindings/net/can/st,stm32-bxcan.yaml

@@ -21,11 +21,22 @@ properties:
 
   st,can-primary:
     description:
-      Primary and secondary mode of the bxCAN peripheral is only relevant
-      if the chip has two CAN peripherals. In that case they share some
-      of the required logic.
+      Primary mode of the bxCAN peripheral is only relevant if the chip has
+      two CAN peripherals in dual CAN configuration. In that case they share
+      some of the required logic.
+      Not to be used if the peripheral is in single CAN configuration.
       To avoid misunderstandings, it should be noted that ST documentation
-      uses the terms master/slave instead of primary/secondary.
+      uses the terms master instead of primary.
+    type: boolean
+
+  st,can-secondary:
+    description:
+      Secondary mode of the bxCAN peripheral is only relevant if the chip
+      has two CAN peripherals in dual CAN configuration. In that case they
+      share some of the required logic.
+      Not to be used if the peripheral is in single CAN configuration.
+      To avoid misunderstandings, it should be noted that ST documentation
+      uses the terms slave instead of secondary.
     type: boolean
 
   reg: