rtc: move date.c from drivers/rtc/ to lib/

In the next commit, rtc_mktime(), for compatibility with linux, will be
implemented using rtc_mktime(), which is no longer drivers/rtc specific.
So move this file under lib/.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index a2b9e19..bc8318d 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1625,6 +1625,7 @@
 config CMD_DATE
 	bool "date"
 	default y if DM_RTC
+	select LIB_DATE
 	help
 	  Enable the 'date' command for getting/setting the time/date in RTC
 	  devices.
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 8778cc7..89e71cc 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -7,6 +7,7 @@
 config DM_RTC
 	bool "Enable Driver Model for RTC drivers"
 	depends on DM
+	select LIB_DATE
 	help
 	  Enable drver model for real-time-clock drivers. The RTC uclass
 	  then provides the rtc_get()/rtc_set() interface, delegating to
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index f97a669..e8875ce 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -7,7 +7,6 @@
 obj-$(CONFIG_$(SPL_TPL_)DM_RTC) += rtc-uclass.o
 
 obj-$(CONFIG_RTC_AT91SAM9_RTT) += at91sam9_rtt.o
-obj-y += date.o
 obj-y += rtc-lib.o
 obj-$(CONFIG_RTC_DAVINCI) += davinci.o
 obj-$(CONFIG_RTC_DS1302) += ds1302.o
diff --git a/lib/Kconfig b/lib/Kconfig
index 55dedcb..2c018cb 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -574,4 +574,7 @@
 	bool "enable fdtdec test"
 	depends on OF_LIBFDT
 
+config LIB_DATE
+	bool
+
 endmenu
diff --git a/lib/Makefile b/lib/Makefile
index e15a189..90d4425 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -117,4 +117,6 @@
 obj-y += vsprintf.o strto.o
 endif
 
+obj-y += date.o
+
 subdir-ccflags-$(CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED) += -O2
diff --git a/drivers/rtc/date.c b/lib/date.c
similarity index 95%
rename from drivers/rtc/date.c
rename to lib/date.c
index c57317d..63af4a1 100644
--- a/drivers/rtc/date.c
+++ b/lib/date.c
@@ -9,8 +9,7 @@
 #include <errno.h>
 #include <rtc.h>
 
-#if defined(CONFIG_CMD_DATE) || defined(CONFIG_DM_RTC) || \
-				defined(CONFIG_TIMESTAMP)
+#if defined(CONFIG_LIB_DATE) || defined(CONFIG_TIMESTAMP)
 
 #define FEBRUARY		2
 #define	STARTOFTIME		1970
@@ -97,4 +96,4 @@
 	return (hours * 60 + tm->tm_min) * 60 + tm->tm_sec;
 }
 
-#endif
+#endif /* CONFIG_LIB_DATE || CONFIG_TIMESTAMP */