dt-bindings: phy-mtk-tphy: remove unused u3phya_ref clock

The u3phya_ref clock is already moved into sub-node, and
renamed as ref clock, no used anymore now, so remove it
to avoid confusion
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>

Documentation/devicetree/bindings/phy/phy-mtk-tphy.txt

@@ -13,10 +13,6 @@ Required properties (controller (parent) node):
 		  "mediatek,mt8173-u3phy";
 		  make use of "mediatek,generic-tphy-v1" on mt2701 instead and
 		  "mediatek,generic-tphy-v2" on mt2712 instead.
- - clocks	: (deprecated, use port's clocks instead) a list of phandle +
-		  clock-specifier pairs, one for each entry in clock-names
- - clock-names	: (deprecated, use port's one instead) must contain
-		  "u3phya_ref": for reference clock of usb3.0 analog phy.
 
 Required nodes	: a sub-node is required for each port the controller
 		  provides. Address range information including the usual