dt-bindings: pinctrl: at91: add sam9x7

Add device tree binding for SAM9X7 pin controller.
Signed-off-by: Varshini Rajendran <varshini.rajendran@microchip.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240223172531.671993-1-varshini.rajendran@microchip.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/pinctrl/atmel,at91-pinctrl.txt

@@ -20,6 +20,7 @@ such as pull-up, multi drive, etc.
 Required properties for iomux controller:
 - compatible: "atmel,at91rm9200-pinctrl" or "atmel,at91sam9x5-pinctrl"
 		or "atmel,sama5d3-pinctrl" or "microchip,sam9x60-pinctrl"
+		or "microchip,sam9x7-pinctrl", "microchip,sam9x60-pinctrl"
 - atmel,mux-mask: array of mask (periph per bank) to describe if a pin can be
   configured in this periph mode. All the periph and bank need to be describe.
 
@@ -120,6 +121,7 @@ Some requirements for using atmel,at91rm9200-pinctrl binding:
 For each bank the required properties are:
 - compatible: "atmel,at91sam9x5-gpio" or "atmel,at91rm9200-gpio" or
   "microchip,sam9x60-gpio"
+  or "microchip,sam9x7-gpio", "microchip,sam9x60-gpio", "atmel,at91rm9200-gpio"
 - reg: physical base address and length of the controller's registers
 - interrupts: interrupt outputs from the controller
 - interrupt-controller: marks the device node as an interrupt controller