drm/amdkfd: Fix a circular lock dependency

Fix a circular lock dependency exposed under userptr memory pressure.
The DQM lock is the only one taken inside the MMU notifier. We need
to make sure that no reclaim is done under this lock, and that
no other locks are taken under which reclaim is possible.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Philip Yang <Philip.Yang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>