dt-bindings: i2c: Add Mediatek MT2701 i2c binding

Add MT2701 i2c binding to i2c-mt6577.txt and there is no need to
modify i2c driver.
Signed-off-by: Jun Gao <jun.gao@mediatek.com>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

Documentation/devicetree/bindings/i2c/i2c-mtk.txt

@@ -4,6 +4,7 @@ The Mediatek's I2C controller is used to interface with I2C devices.
 
 Required properties:
   - compatible: value should be either of the following.
+      "mediatek,mt2701-i2c", "mediatek,mt6577-i2c": for Mediatek mt2701
       "mediatek,mt6577-i2c": for i2c compatible with mt6577.
       "mediatek,mt6589-i2c": for i2c compatible with mt6589.
       "mediatek,mt7623-i2c", "mediatek,mt6577-i2c": for i2c compatible with mt7623.