rtc: pcf2127: add support for spi interface

pcf2127 has selectable I2C-bus and SPI-bus interface support.

This adds support for SPI interface.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index d2cd206..544bd34 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -379,15 +379,6 @@
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-x1205.
 
-config RTC_DRV_PCF2127
-	tristate "NXP PCF2127"
-	help
-	  If you say yes here you get support for the NXP PCF2127/29 RTC
-	  chips.
-
-	  This driver can also be built as a module. If so, the module
-	  will be called rtc-pcf2127.
-
 config RTC_DRV_PCF8523
 	tristate "NXP PCF8523"
 	help
@@ -776,6 +767,16 @@
 	  This driver can also be built as a module.  If so, the module
 	  will be called rtc-ds3232.
 
+config RTC_DRV_PCF2127
+	tristate "NXP PCF2127"
+	depends on RTC_I2C_AND_SPI
+	help
+	  If you say yes here you get support for the NXP PCF2127/29 RTC
+	  chips.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-pcf2127.
+
 comment "Platform RTC drivers"
 
 # this 'CMOS' RTC driver is arch dependent because <asm-generic/rtc.h>