VITIS-13806 Fix helper scripts and return codes for xrt-smi

[rchane]

Problem solved by the commit

https://jira.xilinx.com/browse/VITIS-13806

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

The xrt-smi and xbutil helper scripts weren't trying to get the loader and returned 0 due to a faulty if check.
(e.g. bin is still in the path on Windows MCDM and Linux amdxdna, so we should still be finding the loader)

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

Fixed the if check. This should also preserve the original return behavior for edge platforms.

Risks (if any) associated the changes in the commit

N/A

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

Tested/built on amdxdna and MCDM.

$ xrt-smi configure --pmode performance
ERROR: Please specify a device using --device option
 Available devices:

$ echo $?
1

Documentation impact (if any)

N/A

[rbramand-xilinx]

Thanks for making the changes, checking if the string starts with /usr or /bin works with embedded platforms.

[chvamshi-xilinx]

You cannot remove xbutil as it is still being used in edge platforms. There were concerns in Ops review last week, We still need to keep xbutil for one more release.

[rchane]

You cannot remove xbutil as it is still being used in edge platforms. There were concerns in Ops review last week, We still need to keep xbutil for one more release.

Thank you, Vamshi; I updated the PR and description accordingly.