dt-bindings: sc16is7xx: Add flag to activate IrDA mode

This series of uart controllers is able to work in IrDA mode.
This adds a property to the device tree to enable that feature on
selected ports if needed.
Signed-off-by: Pascal Huerst <pascal.huerst@gmail.com>
Signed-off-by: Daniel Mack <daniel@zonque.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200529055058.1606910-2-daniel@zonque.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/nxp,sc16is7xx.txt

@@ -21,6 +21,8 @@ Optional properties:
   the second cell is used to specify the GPIO polarity:
     0 = active high,
     1 = active low.
+- irda-mode-ports: An array that lists the indices of the port that
+		   should operate in IrDA mode.
 
 Example:
         sc16is750: sc16is750@51 {
@@ -55,6 +57,8 @@ Optional properties:
   the second cell is used to specify the GPIO polarity:
     0 = active high,
     1 = active low.
+- irda-mode-ports: An array that lists the indices of the port that
+		   should operate in IrDA mode.
 
 Example:
 	sc16is750: sc16is750@0 {