image: Drop IMAGE_BOOT_GET_CMDLINE

This is not needed with Kconfig, since we can use IS_ENABLED() easily
enough and the board code is now in a separate file. Update the only place
where this is used and drop it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
2 files changed