dm: rtc: sandbox: Enable real-time clock support

Enable real-time-clock support in sandbox.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/configs/sandbox.h b/include/configs/sandbox.h
index 3bf45a2..ef0efc5 100644
--- a/include/configs/sandbox.h
+++ b/include/configs/sandbox.h
@@ -207,5 +207,6 @@
 
 #define CONFIG_CMD_LZMADEC
 #define CONFIG_CMD_USB
+#define CONFIG_CMD_DATE
 
 #endif