website: Fixed a compile error.

Following the guide step by step in the doc, users will fail on compiling, because DPRINTF must be included before using it.

Change-Id: Ifcd5e68b7b3529c52288aaf02052a286a9e4f5d1
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5-website/+/59213
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Reviewed-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Tested-by: Bobby Bruce <bbruce@ucdavis.edu>
1 file changed