tools/testing/scatterlist: Fix overflow of max segment size

Because SCATTERLIST_MAX_SEGMENT was removed and replaced with UINT_MAX,
the test overflows the max_sgement variable. Remove this case.

Fixes: 7a60c2dd

 ("drm: Remove SCATTERLIST_MAX_SEGMENT")
Link: https://lore.kernel.org/r/20210125120527.836363-1-leon@kernel.org
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>