lava_helper_configs: qemu/mps2-an521: disable the default config

The default config is hanging in lava. Disable the config until we
figure out what's going on.

Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>
Change-Id: Ie98026b3dcee7469b02413376535732c568dd1f1
1 file changed