drm/amd/amdkfd: add/remove kfd queues on start/stop KFD scheduling

Add back kfd queues in start scheduling that originally been
removed on stop scheduling.

Signed-off-by: Shaoyun Liu <shaoyun.liu@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Reviewed-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>