env: Switch the callback static list to Kconfig

Switch the callback static list from the board configuration variable
CFG_ENV_CALLBACK_LIST_STATIC to Kconfig CONFIG_ENV_CALLBACK_LIST_STATIC.

Signed-off-by: Christoph Niedermaier <cniedermaier@dh-electronics.com>
Reviewed-by: Marek Vasut <marex@denx.de>
diff --git a/doc/develop/environment.rst b/doc/develop/environment.rst
index e178346..e46cd39 100644
--- a/doc/develop/environment.rst
+++ b/doc/develop/environment.rst
@@ -18,8 +18,8 @@
 U_BOOT_ENV_CALLBACK macro in your board or driver code.
 
 These callbacks are associated with variables in one of two ways.  The
-static list can be added to by defining CFG_ENV_CALLBACK_LIST_STATIC
-in the board configuration to a string that defines a list of
+static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
+in the board defconfig via menuconfig to a string that defines a list of
 associations.  The list must be in the following format::
 
     entry = variable_name[:callback_name]