fix for multple process example in aws environment

[karthdmg-xilinx]

Problem solved by the commit

• Fix multiple process failure in aws environment
• Increase in delaay for AWS AFI download.
• Fix for reading dynamic aws shell version

Bug / issue (if any) fixed, which PR introduced the bug, how it was discovered

• Large AFI downloads may take more then ~50secs which is the current timeout. Increased the timeout
  to ~120sec specified by AWS team.
• When multiple clients from user space performs AFI downloads simultaneously, usually only one client gets dev lock and performs AFI download while others wait for lock. since in AWS environment, pci rescan happens during first AFI load, this results in ambiguity where device lock gets released during retry of one client and other clients acquire and perform AFI download which are waiting on queue. this results in mailbox timeouts.

How problem was solved, alternative solutions (if any) and why they were rejected

• increase timeout from 50 secs to 120 secs for AFI download failures.
• serialize AWS AFI downloads, such that only one client executes the entire AFI download cycle.

Risks (if any) associated the changes in the commit

None

What has been tested and how, request additional testing if necessary

Tested entire regression test suite of AWS.

Documentation impact (if any)

None