dt-bindings: pinctrl: ocelot: Add Sparx5 SoC support

This adds documentation for the "compatible" value designated for Sparx5
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Lars Povlsen <lars.povlsen@microchip.com>
Link: https://lore.kernel.org/r/20200513125532.24585-8-lars.povlsen@microchip.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/pinctrl/mscc,ocelot-pinctrl.txt

@@ -2,8 +2,8 @@ Microsemi Ocelot pin controller Device Tree Bindings
 ----------------------------------------------------
 
 Required properties:
- - compatible		: Should be "mscc,ocelot-pinctrl" or
-				"mscc,jaguar2-pinctrl"
+ - compatible		: Should be "mscc,ocelot-pinctrl",
+			  "mscc,jaguar2-pinctrl" or "microchip,sparx5-pinctrl"
  - reg			: Address and length of the register set for the device
  - gpio-controller	: Indicates this device is a GPIO controller
  - #gpio-cells		: Must be 2.