Docker/CI: Only test Xtensa on amd64 hosts

The xtensa architecture is interesting in that the platforms we support
are only valid on the binary-only toolchains as the DC233C instruction
set requires those toolchains (and not the FSF instruction set). Only
install the binary toolchain on amd64 hosts and only run the tests on
them as well.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
2 files changed