Given control stack is now in the userspace context save restore area
on GFX10, the same as GFX8, it is not needed to copy it back to userspace.
Signed-off-by: Yong Zhao <Yong.Zhao@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>