rtc: simplify getting .drvdata

We should get drvdata from struct device directly. Going via
platform_device is an unneeded step back and forth.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Acked-by: Michal Simek <michal.simek@xilinx.com> (for zynqmp)
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
diff --git a/drivers/rtc/rtc-test.c b/drivers/rtc/rtc-test.c
index 3a2da4c..390f928 100644
--- a/drivers/rtc/rtc-test.c
+++ b/drivers/rtc/rtc-test.c
@@ -84,8 +84,7 @@ static ssize_t test_irq_store(struct device *dev,
 				const char *buf, size_t count)
 {
 	int retval;
-	struct platform_device *plat_dev = to_platform_device(dev);
-	struct rtc_device *rtc = platform_get_drvdata(plat_dev);
+	struct rtc_device *rtc = dev_get_drvdata(dev);
 
 	retval = count;
 	if (strncmp(buf, "tick", 4) == 0 && rtc->pie_enabled)