rtc: add support for s35392a

Add support for S35392A RTC. The driver supports both U-Boot driver
models.

Signed-off-by: Nandor Han <nandor.han@ge.com>
Signed-off-by: Martyn Welch <martyn.welch@collabora.co.uk>
Cc: Heiko Schocher <hs@denx.de>
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index d06130c7..2964bb2 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -30,4 +30,10 @@
 	  Support for Dallas Semiconductor (now Maxim) DS1307 and DS1338/9 and
 	  compatible Real Time Clock devices.
 
+config RTC_S35392A
+	bool "Enable S35392A driver"
+	select BITREVERSE
+	help
+	  Enable s35392a driver which provides rtc get and set function.
+
 endmenu