dt-bindings: display: mediatek: add dsi reset optional property

Update device tree binding documentation for the dsi to add the optional
property to reset the dsi controller.
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210930103105.v4.3.Ifec72a83f224b62f24cfc967edfe78c5d276b2e3@changeidSigned-off-by: Matthias Brugger <matthias.bgg@gmail.com>

Documentation/devicetree/bindings/display/mediatek/mediatek,dsi.txt

@@ -19,6 +19,11 @@ Required properties:
   Documentation/devicetree/bindings/graph.txt. This port should be connected
   to the input port of an attached DSI panel or DSI-to-eDP encoder chip.
 
+Optional properties:
+- resets: list of phandle + reset specifier pair, as described in [1].
+
+[1] Documentation/devicetree/bindings/reset/reset.txt
+
 MIPI TX Configuration Module
 ============================
 
@@ -45,6 +50,7 @@ dsi0: dsi@1401b000 {
 	clocks = <&mmsys MM_DSI0_ENGINE>, <&mmsys MM_DSI0_DIGITAL>,
 		 <&mipi_tx0>;
 	clock-names = "engine", "digital", "hs";
+	resets = <&mmsys MT8173_MMSYS_SW0_RST_B_DISP_DSI0>;
 	phys = <&mipi_tx0>;
 	phy-names = "dphy";