Documentation: devicetree: dwc2: Deprecate g-tx-fifo-size

This property is not needed because the periodic fifos are not
configurable. So it was incorrect to add this property in the first
place.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

Documentation/devicetree/bindings/usb/dwc2.txt

@@ -26,7 +26,10 @@ Refer to phy/phy-bindings.txt for generic phy consumer properties
 - g-use-dma: enable dma usage in gadget driver.
 - g-rx-fifo-size: size of rx fifo size in gadget mode.
 - g-np-tx-fifo-size: size of non-periodic tx fifo size in gadget mode.
-- g-tx-fifo-size: size of periodic tx fifo per endpoint (except ep0) in gadget mode.
+
+Deprecated properties:
+- g-tx-fifo-size: size of periodic tx fifo per endpoint (except ep0)
+  in gadget mode.
 
 Example: