`make clean` never thoroughly removed LinuxBoot build artifacts. This
change checks for kernel directories present in the project directory
and deletes all of them, if found.
Signed-off-by: Patrik Tesarik <patrik.tesarik@9elements.com>
Change-Id: Ia056ac6608e3631dfc270ba5c2f32216c3e1ac50
Reviewed-on: https://review.coreboot.org/c/coreboot/+/65098
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
f5c2f253a7