i2c: designware: Move reg-space remapping into a dedicated function

This is a preparation patch before adding a quirk with custom registers
map creation required for the Baikal-T1 System I2C support.
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

drivers/i2c/busses/i2c-designware-platdrv.c

@@ -108,6 +108,15 @@ static void dw_i2c_plat_pm_cleanup(struct dw_i2c_dev *dev)
 		pm_runtime_put_noidle(dev->dev);
 }
 
+static int dw_i2c_plat_request_regs(struct dw_i2c_dev *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev->dev);
+
+	dev->base = devm_platform_ioremap_resource(pdev, 0);
+
+	return PTR_ERR_OR_ZERO(dev->base);
+}
+
 static int dw_i2c_plat_probe(struct platform_device *pdev)
 {
 	struct dw_i2c_platform_data *pdata = dev_get_platdata(&pdev->dev);
@@ -125,15 +134,14 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	dev->flags = (uintptr_t)device_get_match_data(&pdev->dev);
-
-	dev->base = devm_platform_ioremap_resource(pdev, 0);
-	if (IS_ERR(dev->base))
-		return PTR_ERR(dev->base);
-
 	dev->dev = &pdev->dev;
 	dev->irq = irq;
 	platform_set_drvdata(pdev, dev);
 
+	ret = dw_i2c_plat_request_regs(dev);
+	if (ret)
+		return ret;
+
 	dev->rst = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
 	if (IS_ERR(dev->rst))
 		return PTR_ERR(dev->rst);