drm/amdkfd: Move the control stack on GFX10 to userspace buffer

The GFX10 does not require the control stack to be right after mqd
buffer any more, so move it back to usersapce allocated CSWR buffer.

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>