drm/amdkfd: Fix MQD updates

When a queue is mapped, the MQD is owned by the FW. The FW overwrites
the MQD on the next unmap operation. Therefore the queue must be
unmapped before updating the MQD.

For the non-HWS case, also fix disabling of queues and creation of
queues in disabled state.

Signed-off-by: Oak Zeng <Oak.Zeng@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>