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/Makefile b/drivers/rtc/Makefile
index 003e31a..7a8f97a 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -49,5 +49,6 @@
 obj-$(CONFIG_RTC_RV3029) += rv3029.o
 obj-$(CONFIG_RTC_RX8025) += rx8025.o
 obj-$(CONFIG_RTC_S3C24X0) += s3c24x0_rtc.o
+obj-$(CONFIG_RTC_S35392A) += s35392a.o
 obj-$(CONFIG_SANDBOX) += sandbox_rtc.o
 obj-$(CONFIG_RTC_X1205) += x1205.o