global: Migrate CONFIG_EXTRA_ENV_SETTINGS to CFG

Perform a simple rename of CONFIG_EXTRA_ENV_SETTINGS to CFG_EXTRA_ENV_SETTINGS

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/doc/develop/distro.rst b/doc/develop/distro.rst
index bc72aa9..8016aca 100644
--- a/doc/develop/distro.rst
+++ b/doc/develop/distro.rst
@@ -214,7 +214,7 @@
 
 The U-Boot "syslinux" and "pxe boot" commands require a number of environment
 variables be set. Default values for these variables are often hard-coded into
-CONFIG_EXTRA_ENV_SETTINGS in the board's U-Boot configuration file, so that
+CFG_EXTRA_ENV_SETTINGS in the board's U-Boot configuration file, so that
 the user doesn't have to configure them.
 
 fdt_addr: