rtc: test: make array pdev static

The array pdev is local to the source and does not need to be in
global scope, so make it static.

Cleans up sparse warning:
symbol 'pdev' was not declared. Should it be static?
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/rtc-test.c

@@ -22,7 +22,7 @@ struct rtc_test_data {
 	bool alarm_en;
 };
 
-struct platform_device *pdev[MAX_RTC_TEST];
+static struct platform_device *pdev[MAX_RTC_TEST];
 
 static int test_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 {