drm/amdkfd: Differentiate b/t sdma_id and sdma_queue_id

sdma_queue_id is sdma queue index inside one sdma engine.
sdma_id is sdma queue index among all sdma engines. Use
those two names properly.

Signed-off-by: Oak Zeng <ozeng@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>