rtc: stmp3xxx select STMP_DEVICE

rtc-stmp3xxx depends on lib/stmp_device, select it.
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/Kconfig

@@ -1396,6 +1396,7 @@ config RTC_DRV_COH901331
 config RTC_DRV_STMP
 	tristate "Freescale STMP3xxx/i.MX23/i.MX28 RTC"
 	depends on ARCH_MXS
+	select STMP_DEVICE
 	help
 	  If you say yes here you will get support for the onboard
 	  STMP3xxx/i.MX23/i.MX28 RTC.