cmd: add Kconfig option for 'date' command

Signed-off-by: Chris Packham <judge.packham@gmail.com>
[trini: default y if DM_RTC, re-sync]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/mx28evk_defconfig b/configs/mx28evk_defconfig
index fd7ec78..c5fe559 100644
--- a/configs/mx28evk_defconfig
+++ b/configs/mx28evk_defconfig
@@ -28,6 +28,7 @@
 CONFIG_CMD_PING=y
 CONFIG_CMD_BMP=y
 CONFIG_CMD_CACHE=y
+CONFIG_CMD_DATE=y
 CONFIG_CMD_EXT4=y
 CONFIG_CMD_EXT4_WRITE=y
 CONFIG_CMD_FAT=y