drm/amdkfd: CRIU Refactor restore BO function

Refactor CRIU restore BO to reduce identation.

Signed-off-by: David Yat Sin <david.yatsin@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>