As support of ARC HS38 in OpenWRT/Lede matures we don't need
debug-only output binaries any longer, so purging vmlinux for
AXS10x boards.
As for uImage for nSIM it makes completely no sense because there's no
way to run U-Boot on nSIM.
So we remove add_archs38_XXX scripts making code more compact and
cleaner.
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>