drm/amdgpu: Add GPUVM memory management functions for KFD

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>

drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c

@@ -58,6 +58,7 @@ int amdgpu_amdkfd_init(void)
 #else
 	ret = -ENOENT;
 #endif
+	amdgpu_amdkfd_gpuvm_init_mem_limits();
 
 	return ret;
 }