Aperture locking is too fine-grained, it has race between find userptr
and allocate userptr object.
Change _fmm_allocate_device and fmm_allocate_memory_object to not take
the aperture lock, the callers take it, this implements an atomic find
userptr or allocate a new one.
Change-Id: I6773404e22c1f4382a211c5a9817df23c5534a2a
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
[ROCm/ROCR-Runtime commit: c4d5ee28f0]