rtc: atcrtc100: Fix signedness bug in probe()

The "atcrtc_dev->alarm_irq" variable is an unsigned int but it needs to
be signed for the error handling to work.  Use the "ret" variable
instead.

Fixes: 7adca70 ("rtc: atcrtc100: Add ATCRTC100 RTC driver")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://patch.msgid.link/aRxPGBEX8hbY6sjV@stanley.mountain
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: Dan Carpenter

drivers/rtc/rtc-atcrtc100.c

@@ -296,10 +296,12 @@ static int atcrtc_probe(struct platform_device *pdev)
 				     "Failed to initialize RTC: unsupported hardware ID 0x%x\n",
 				     rtc_id);
 
-	atcrtc_dev->alarm_irq = platform_get_irq(pdev, 1);
-	if (atcrtc_dev->alarm_irq < 0)
-		return dev_err_probe(&pdev->dev, atcrtc_dev->alarm_irq,
+	ret = platform_get_irq(pdev, 1);
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret,
 				     "Failed to get IRQ for alarm\n");
+	atcrtc_dev->alarm_irq = ret;
+
 	ret = devm_request_irq(&pdev->dev,
 			       atcrtc_dev->alarm_irq,
 			       atcrtc_alarm_isr,