net: dsa: ksz: Add optional reset GPIO to Microchip KSZ switch binding

Add optional reset GPIO, as such a signal is available on the KSZ switches.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Woojung Huh <Woojung.Huh@microchip.com>
Cc: David S. Miller <davem@davemloft.net>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/dsa/ksz.txt

@@ -8,6 +8,10 @@ Required properties:
   - "microchip,ksz9477"
   - "microchip,ksz9897"
 
+Optional properties:
+
+- reset-gpios		: Should be a gpio specifier for a reset line
+
 See Documentation/devicetree/bindings/net/dsa/dsa.txt for a list of additional
 required and optional properties.