ASACORE-974: Fix EACK mask computation

Plus, make sure that persist timer is scheduled when there
are no pending data retransmits.

Change-Id: I42d65891783ef13aace7197bda114c1528bef159
Signed-off-by: Inga Stotland <ingas@qce.qualcomm.com>
Merge "ASACORE-974: Fix EACK mask computation" into feature/udp_transport