Convert CONFIG_CMD_SH_ZIMAGEBOOT to Kconfig
This converts the following to Kconfig:
CONFIG_CMD_SH_ZIMAGEBOOT
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>