dt-bindings: mmc: mtk-sd: Add hs400 dly3 setting

Add hs400 dly3 setting for mtk-sd yaml
Signed-off-by: Wenbin Mei <wenbin.mei@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20210917124803.22871-2-wenbin.mei@mediatek.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/mtk-sd.yaml

@@ -119,6 +119,18 @@ properties:
       If present, HS400 command responses are sampled on rising edges.
       If not present, HS400 command responses are sampled on falling edges.
 
+  mediatek,hs400-ds-dly3:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Gear of the third delay line for DS for input data latch in data
+      pad macro, there are 32 stages from 0 to 31.
+      For different corner IC, the time is different about one step, it is
+      about 100ps.
+      The value is confirmed by doing scan and calibration to find a best
+      value with corner IC and it is valid only for HS400 mode.
+    minimum: 0
+    maximum: 31
+
   mediatek,latch-ck:
     $ref: /schemas/types.yaml#/definitions/uint32
     description: