dt-bindings: display: mediatek: get mipitx calibration data from nvmem

Add properties to get get mipitx calibration data.
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NJitao Shi <jitao.shi@mediatek.com>
Signed-off-by: NChun-Kuang Hu <chunkuang.hu@kernel.org>

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

@@ -36,6 +36,9 @@ Required properties:
 Optional properties:
 - drive-strength-microamp: adjust driving current, should be 3000 ~ 6000. And
 						   the step is 200.
+- nvmem-cells: A phandle to the calibration data provided by a nvmem device. If
+               unspecified default values shall be used.
+- nvmem-cell-names: Should be "calibration-data"
 
 Example:
 
@@ -47,6 +50,8 @@ mipi_tx0: mipi-dphy@10215000 {
 	#clock-cells = <0>;
 	#phy-cells = <0>;
 	drive-strength-microamp = <4600>;
+	nvmem-cells= <&mipi_tx_calibration>;
+	nvmem-cell-names = "calibration-data";
 };
 
 dsi0: dsi@1401b000 {