drm/amdkfd: Fix sdma queue map issue

Previous codes assumes there are two sdma engines.
This is not true e.g., Raven only has 1 SDMA engine.
Fix the issue by using sdma engine number info in
device_info.

Signed-off-by: Oak Zeng <Oak.Zeng@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>