dt-bindings: net: micrel: add coma-mode-gpios property

The LAN8814 has a coma mode pin which is used to put the PHY into
isolate and power-down mode. Usually strapped to be asserted by default.
A GPIO is then used to take the PHY out of this mode.
Signed-off-by: Michael Walle <michael@walle.cc>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Documentation/devicetree/bindings/net/micrel.txt

@@ -45,3 +45,12 @@ Optional properties:
 
 	In fiber mode, auto-negotiation is disabled and the PHY can only work in
 	100base-fx (full and half duplex) modes.
+
+ - coma-mode-gpios: If present the given gpio will be deasserted when the
+		    PHY is probed.
+
+	Some PHYs have a COMA mode input pin which puts the PHY into
+	isolate and power-down mode. On some boards this input is connected
+	to a GPIO of the SoC.
+
+	Supported on the LAN8814.