drm/nouveau/nouveau: fix the start/end range for migration

drm/nouveau/nouveau: fix the start/end range for migration

[ Upstream commit cfa736f5a6f31ca8a05459b5720aac030247ad1b ]

The user level OpenCL code shouldn't have to align start and end
addresses to a page boundary. That is better handled in the nouveau
driver. The npages field is also redundant since it can be computed
from the start and end addresses.

Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>