drm/amdkfd: Allocate MQD trunk for HIQ and SDMA

MEC FW for some new asic requires all SDMA MQDs to be in a continuous
trunk of memory right after HIQ MQD. Add a field in device queue manager
to hold the HIQ/SDMA MQD memory object and allocate MQD trunk on device
queue manager initialization.

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>