kconfig: move CONFIG_CMD_EXPORTENV to Kconfig

Since CONFIG_CMD_EXPORTENV is defined in config_cmd_defaults.h,
it should be enabled for all the boards except bf506f-ezkit
that undefs it explicitely.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>

common/Kconfig

@@ -13,4 +13,10 @@ config CMD_CRC32
 	help
 	  Compute CRC32.
 
+config CMD_EXPORTENV
+	bool "Enable env export command"
+	default y
+	help
+	  Export environments.
+
 endmenu

configs/bf506f-ezkit_defconfig

 CONFIG_BLACKFIN=y
 CONFIG_TARGET_BF506F_EZKIT=y
 # CONFIG_CMD_BOOTM is not set
+# CONFIG_CMD_EXPORTENV is not set

include/config_cmd_defaults.h

@@ -9,7 +9,6 @@
 #ifndef _CONFIG_CMD_DEFAULTS_H_
 #define _CONFIG_CMD_DEFAULTS_H_
 
-#define CONFIG_CMD_EXPORTENV 1
 #define CONFIG_CMD_GO 1
 #define CONFIG_CMD_IMPORTENV 1
 

include/configs/bf506f-ezkit.h

@@ -85,7 +85,6 @@
  */
 #define CONFIG_ENV_IS_NOWHERE
 #define CONFIG_ENV_SIZE 0x400
-#undef CONFIG_CMD_EXPORTENV
 #undef CONFIG_CMD_IMPORTENV