dt-bindings: net: dsa: qca8k: Document qca,led-open-drain binding

Document new binding qca,ignore-power-on-sel used to ignore
power on strapping and use sw regs instead.
Document qca,led-open.drain to set led to open drain mode, the
qca,ignore-power-on-sel is mandatory with this enabled or an error will
be reported.
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/devicetree/bindings/net/dsa/qca8k.txt

@@ -13,6 +13,17 @@ Required properties:
 Optional properties:
 
 - reset-gpios: GPIO to be used to reset the whole device
+- qca,ignore-power-on-sel: Ignore power on pin strapping to configure led open
+                           drain or eeprom presence. This is needed for broken
+                           devices that have wrong configuration or when the oem
+                           decided to not use pin strapping and fallback to sw
+                           regs.
+- qca,led-open-drain: Set leds to open-drain mode. This requires the
+                      qca,ignore-power-on-sel to be set or the driver will fail
+                      to probe. This is needed if the oem doesn't use pin
+                      strapping to set this mode and prefers to set it using sw
+                      regs. The pin strapping related to led open drain mode is
+                      the pin B68 for QCA832x and B49 for QCA833x
 
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