v2:
* Removed unused flags from struct kgd_mem
* Updated some comments
* Added a check to unmap_memory_from_gpu whether BO was mapped

v3: add mutex_destroy in relevant places

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>