website: Added video link for "Towards full-sy..."

The old link for "Towards full-system discrete GPU simulation" was
wrong and pointed towards the talk for "The AMD gem5 GPU Simulator".
This has been fixed. There are now two videos, one for each
presentation. They will share the same timeslot.

Change-Id: I4a233388a124d5a7a104f1982980b88e86ad2559
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/29813
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: Bobby R. Bruce <bbruce@ucdavis.edu>
1 file changed