[Description]

solve the big file transfer issue using ISCSI
[Impaction]
change the control flow on IScsiExecuteScsiCommand  function
[Reference Info]
The original design incorrectly uses a timer (its span is usually 2 seconds) to ensure the timely execution of CMD PDU send by initiator. For example: When initiator delivers a CMD PDU(WRITE command) in which the ExpDataXferLength filed is larger than DataSegmentLength field, according to ISCSI protocol spec, the target will respond it with a R2T PDU which is followed by a sequential DATA-OUT PDUs. In this situation, the original code may loop to deal with the arrival packet until initiator receives a RESPONSE PDU or the timer is expired. This way may cause the bigger file is more likely to fail.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@5044 6f19259b-4bc3-4df7-8a09-765794883524