i2c: mediatek: mt65xx: add optional vbus-supply

Add vbus-supply which provides power to SCL/SDA. Pass this regulator
into core so it can be turned on/off for low power mode support.
Signed-off-by: NHsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: NMatthias Brugger <matthias.bgg@gmail.com>
Reviewed-by: NQii Wang <qii.wang@mediatek.com>
Signed-off-by: NWolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-mt65xx.c

@@ -1220,6 +1220,13 @@ static int mtk_i2c_probe(struct platform_device *pdev)
 	i2c->adap.quirks = i2c->dev_comp->quirks;
 	i2c->adap.timeout = 2 * HZ;
 	i2c->adap.retries = 1;
+	i2c->adap.bus_regulator = devm_regulator_get_optional(&pdev->dev, "vbus");
+	if (IS_ERR(i2c->adap.bus_regulator)) {
+		if (PTR_ERR(i2c->adap.bus_regulator) == -ENODEV)
+			i2c->adap.bus_regulator = NULL;
+		else
+			return PTR_ERR(i2c->adap.bus_regulator);
+	}
 
 	ret = mtk_i2c_parse_dt(pdev->dev.of_node, i2c);
 	if (ret)