rtc: sc27xx: Add Spreadtrum SC27xx PMIC RTC driver

This patch adds the Spreadtrum RTC driver, which embedded in the
Spreadtrum SC27xx series PMICs.

Signed-off-by: Baolin Wang <baolin.wang@spreadtrum.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 0b5acd6..5cf6b0a 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -145,6 +145,7 @@
 obj-$(CONFIG_RTC_DRV_S3C)	+= rtc-s3c.o
 obj-$(CONFIG_RTC_DRV_S5M)	+= rtc-s5m.o
 obj-$(CONFIG_RTC_DRV_SA1100)	+= rtc-sa1100.o
+obj-$(CONFIG_RTC_DRV_SC27XX)	+= rtc-sc27xx.o
 obj-$(CONFIG_RTC_DRV_SH)	+= rtc-sh.o
 obj-$(CONFIG_RTC_DRV_SIRFSOC)	+= rtc-sirfsoc.o
 obj-$(CONFIG_RTC_DRV_SNVS)	+= rtc-snvs.o