sgdisk 0.8.10.2 from AOSP doesn't support short options, failing with
errors like this:
sgdisk: invalid option -- 'U'
Test fails due to that error. Let's use long options to make the test
work with any sgdisk version.
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Acked-by: Stephen Warren <swarren@nvidia.com>