lib: kconfig: Mention CONFIG_ADDR_MAP limitation in the help
Mention that CONFIG_ADDR_MAP only works in the post-relocation phase.
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>