drm/amdkfd: Fix memory leakage

This patch fixes potential memory leakage and seg fault
in  _gpuvm_import_dmabuf() function

Fixes: d4ec4bdc ("drm/amdkfd: Allow access for mmapping KFD BOs")
Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -2204,7 +2204,7 @@ int amdgpu_amdkfd_gpuvm_import_dmabuf(struct amdgpu_device *adev,
 
 	ret = drm_vma_node_allow(&obj->vma_node, drm_priv);
 	if (ret) {
-		kfree(mem);
+		kfree(*mem);
 		return ret;
 	}