drm/amdkfd: Fix CRIU restore op due to doorbell offset

Recently introduced change to allocate doorbells only when the first
queue is created or mapped for CPU / GPU access, did not consider
Checkpoint Restore scenario completely. This fix allows the CRIU restore
operation by extending the doorbell optimization to CRIU restore
scenario.

Fixes: 16f00131 ("drm/amdkfd: Allocate doorbells only when needed")

Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>