Add helper function kfd_queue_acquire_buffers to get queue wptr_bo
reference from queue write_ptr if it is mapped to the KFD node with
expected size.

Add wptr_bo to structure queue_properties because structure queue is
allocated after queue buffers are validated, then we can remove wptr_bo
parameter from pqm_create_queue.

Rename structure queue wptr_bo_gart to hold wptr_bo reference for GART
mapping and umapping. Move MES wptr_bo_gart mapping to init_user_queue,
the same location with queue ctx_bo GART mapping.
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>