drm/amdgpu: clean up the amdgpu_cs_parser_bos

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu: clean up the amdgpu_cs_parser_bos In low memory conditions, kmalloc can fail. In such conditions unlock the mutex for a clean exit. We do not need to amdgpu_bo_list_put as it's been handled in the amdgpu_cs_parser_fini.