Convert CONFIG_CMD_ENV_CALLBACK to Kconfig

This converts the following to Kconfig:
   CONFIG_CMD_ENV_CALLBACK

Signed-off-by: Simon Glass <sjg@chromium.org>

README

@@ -833,7 +833,6 @@ The following options need to be configured:
 		CONFIG_CMD_ECHO		  echo arguments
 		CONFIG_CMD_EDITENV	  edit env variable
 		CONFIG_CMD_ELF		* bootelf, bootvx
-		CONFIG_CMD_ENV_CALLBACK	* display details about env callbacks
 		CONFIG_CMD_ENV_FLAGS	* display details about env flags
 		CONFIG_CMD_ENV_EXISTS	* check existence of env variable
 		CONFIG_CMD_EXPORTENV	* export the environment

cmd/Kconfig

@@ -314,6 +314,14 @@ config CMD_ENV_EXISTS
 	  Check if a variable is defined in the environment for use in
 	  shell scripting.
 
+config CMD_ENV_CALLBACK
+	bool "env callbacks - print callbacks and their associated variables"
+	help
+	  Some environment variable have callbacks defined by
+	  U_BOOT_ENV_CALLBACK. These are called when the variable changes.
+	  For example changing "baudrate" adjust the serial baud rate. This
+	  command lists the currently defined callbacks.
+
 endmenu
 
 menu "Memory commands"

configs/sandbox_defconfig

@@ -22,6 +22,7 @@ CONFIG_CMD_BOOTZ=y
 # CONFIG_CMD_IMLS is not set
 CONFIG_CMD_ASKENV=y
 CONFIG_CMD_GREPENV=y
+CONFIG_CMD_ENV_CALLBACK=y
 CONFIG_CMD_MD5SUM=y
 CONFIG_LOOPW=y
 CONFIG_CMD_MEMTEST=y

configs/sandbox_noblk_defconfig

@@ -22,6 +22,7 @@ CONFIG_CMD_BOOTZ=y
 # CONFIG_CMD_IMLS is not set
 CONFIG_CMD_ASKENV=y
 CONFIG_CMD_GREPENV=y
+CONFIG_CMD_ENV_CALLBACK=y
 CONFIG_CMD_MD5SUM=y
 CONFIG_LOOPW=y
 CONFIG_CMD_MEMTEST=y

configs/sandbox_spl_defconfig

@@ -30,6 +30,7 @@ CONFIG_CMD_BOOTZ=y
 # CONFIG_CMD_IMLS is not set
 CONFIG_CMD_ASKENV=y
 CONFIG_CMD_GREPENV=y
+CONFIG_CMD_ENV_CALLBACK=y
 CONFIG_CMD_MD5SUM=y
 CONFIG_LOOPW=y
 CONFIG_CMD_MEMTEST=y

include/configs/sandbox.h

@@ -108,7 +108,6 @@
 #define CONFIG_CMD_SANDBOX
 
 #define CONFIG_CMD_ENV_FLAGS
-#define CONFIG_CMD_ENV_CALLBACK
 
 #define CONFIG_BOOTARGS ""
 

scripts/config_whitelist.txt

@@ -383,7 +383,6 @@ CONFIG_CM922T_XA10
 CONFIG_CMDLINE_EDITING
 CONFIG_CMDLINE_PS_SUPPORT
 CONFIG_CMDLINE_TAG
-CONFIG_CMD_ENV_CALLBACK
 CONFIG_CMD_ENV_FLAGS
 CONFIG_CMD_ERRATA
 CONFIG_CMD_ESBC_VALIDATE