arm: kirkwood: Enable bootstd and other modernization for OpenRD boards

Enable bootstd for OpenRD boards
Update defconfigs to the latest u-boot requirements
Remove JFFS2 support. See JFFS2 Vulnerability[1].
Move default envs to text-base environment

[1] https://lore.kernel.org/u-boot/20241114233005.GN3600562@bill-the-cat/T/#m2fc25da1d2c019bc3cd8676991fdd64b8a21aa9b

Signed-off-by: Tony Dinh <mibodhi@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
6 files changed