virgl: use debug_printf instead of fprintf

While we're at it, prefix the string with "VIRGL: ", to match similar
code elsewhere in virgl.

Signed-off-by: Erik Faye-Lund <erik.faye-lund@collabora.com>
Reviewed-by: Gurchetan Singh <gurchetansingh@chromium.org>
15 jobs for !619 with transfer-bind-cleanups in 15 minutes and 23 seconds (queued for 1 second)
merge request