rtc: max8907: add missing select REGMAP_IRQ

I have hit the following build error:
armv7a-hardfloat-linux-gnueabi-ld: drivers/rtc/rtc-max8907.o: in function `max8907_rtc_probe':
rtc-max8907.c:(.text+0x400): undefined reference to `regmap_irq_get_virq'

max8907 should select REGMAP_IRQ

Fixes: 94c01ab6 ("rtc: add MAX8907 RTC driver")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Link: https://lore.kernel.org/r/1584545209-20433-1-git-send-email-clabbe@baylibre.comSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/rtc/Kconfig

@@ -327,6 +327,7 @@ config RTC_DRV_MAX6900
 config RTC_DRV_MAX8907
 	tristate "Maxim MAX8907"
 	depends on MFD_MAX8907 || COMPILE_TEST
+	select REGMAP_IRQ
 	help
 	  If you say yes here you will get support for the
 	  RTC of Maxim MAX8907 PMIC.