The version of the Zephyr SDK that is used is quite old and Zephyr
hasn't been really used. Thus, drop it and also its dependencies from
u-boot.
Change-Id: Ie498d687e1566133adf650166117d8f68fcfdaf6
Signed-off-by: Felix Singer <felixsinger@posteo.net>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/73979
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-by: Patrick Georgi <patrick@coreboot.org>
a87da91719