drm/amdkfd: Move non-sdma mqd allocation out of init_mqd

This is preparation work to introduce more mqd allocation
scheme

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>