Current code assume that all (except last) packets are of the same size.
This is definitely wrong. Replace SACK code with a new one, that does
not rely on this assumption. Also this code uses less memory.
Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevetskiy@iopsys.eu>
Reviewed-by: Simon Glass <sjg@chromium.org>