drm/amdkfd: Update queue_count before mapping queues

map_queues_cpsch uses the queue_count to decide whether to upload
a new runlist. So update the counter before calling it.

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>