gpio: gpio-xilinx: Check return value of of_property_read_u32

In two different instances the return value of "of_property_read_u32"
API was neither captured nor checked.
Fixed it by capturing the return value and then checking for any error.

Signed-off-by: Srinivas Neeli <srinivas.neeli@xilinx.com>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Addresses-Coverity: "check_return"
Link: https://lore.kernel.org/r/1605201148-4508-9-git-send-email-srinivas.neeli@xilinx.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-xilinx.c

@@ -298,7 +298,8 @@ static int xgpio_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, chip);
 
 	/* Update GPIO state shadow register with default value */
-	of_property_read_u32(np, "xlnx,dout-default", &chip->gpio_state[0]);
+	if (of_property_read_u32(np, "xlnx,dout-default", &chip->gpio_state[0]))
+		chip->gpio_state[0] = 0x0;
 
 	/* Update GPIO direction shadow register with default value */
 	if (of_property_read_u32(np, "xlnx,tri-default", &chip->gpio_dir[0]))
@@ -318,8 +319,9 @@ static int xgpio_probe(struct platform_device *pdev)
 
 	if (is_dual) {
 		/* Update GPIO state shadow register with default value */
-		of_property_read_u32(np, "xlnx,dout-default-2",
-				     &chip->gpio_state[1]);
+		if (of_property_read_u32(np, "xlnx,dout-default-2",
+					 &chip->gpio_state[1]))
+			chip->gpio_state[1] = 0x0;
 
 		/* Update GPIO direction shadow register with default value */
 		if (of_property_read_u32(np, "xlnx,tri-default-2",