gpio: mb86s7x: Use devm_clk_get_optional() to get the input clock

Simplify the code which fetches the input clock by using
devm_clk_get_optional(). If no input clock is present
devm_clk_get_optional() will return NULL instead of an error
which matches the behavior of the old code.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200512182623.54990-1-andriy.shevchenko@linux.intel.comSigned-off-by: NLinus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-mb86s7x.c

@@ -168,15 +168,13 @@ static int mb86s70_gpio_probe(struct platform_device *pdev)
 	if (IS_ERR(gchip->base))
 		return PTR_ERR(gchip->base);
 
-	if (!has_acpi_companion(&pdev->dev)) {
-		gchip->clk = devm_clk_get(&pdev->dev, NULL);
-		if (IS_ERR(gchip->clk))
-			return PTR_ERR(gchip->clk);
-
-		ret = clk_prepare_enable(gchip->clk);
-		if (ret)
-			return ret;
-	}
+	gchip->clk = devm_clk_get_optional(&pdev->dev, NULL);
+	if (IS_ERR(gchip->clk))
+		return PTR_ERR(gchip->clk);
+
+	ret = clk_prepare_enable(gchip->clk);
+	if (ret)
+		return ret;
 
 	spin_lock_init(&gchip->lock);