drm/amdkfd: Preserve cp_hqd_pq_control on update_mqd

When userspace applications call AMDKFD_IOC_UPDATE_QUEUE. Preserve
bitfields that do not need to be modified as they contain flags to
track queue states that are used by CP FW.

Signed-off-by: David Yat Sin <David.YatSin@amd.com>
Reviewed-by: Jay Cornwall <jay.cornwall@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 81508279)
Cc: stable@vger.kernel.org