roc-hcc-2.7.2: Fix upgrade postinst (#1253)

* fix upgrade action in the postinst script
* clean up and fix postinst script not creating symlinks in some situations
* [RPM]fix prerm script incorrectly deleting symlinks during an upgrade

Change-Id: I6aee040dc6ac8363d58ccaf35d4a0d81274e5ea3