drm/amdkfd: Disable CP/SDMA ring/doorbell in MQD

The MQD represents an inactive context and should not have ring or
doorbell enable bits set. Doing so interferes with HWS which streams
the MQD onto the HQD. If enable bits are set this activates the ring
or doorbell before the HQD is fully configured.

Signed-off-by: Jay Cornwall <Jay.Cornwall@amd.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>