python: Improve the print statements in downloader.py
python: Improve the print statements in downloader.py

Most importantly, these print statements now make clear to the user
where the resources are being downloaded to.

Change-Id: Id2661d2567a7ea5ee3157142dc91e814e3e2edaf
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/51370
Reviewed-by: Bobby R. Bruce <b9dba908ffb6c6d8ffe449cc88b3709c13c485c2@ucdavis.edu>
Maintainer: Bobby R. Bruce <b9dba908ffb6c6d8ffe449cc88b3709c13c485c2@ucdavis.edu>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5