protocol: drop reference to wl_drm

Change the wl_drm reference to linux-dmabuf. wl_drm is a legacy,
private Mesa protocol that shouldn't be used by regular clients.

Signed-off-by: Simon Ser <contact@emersion.fr>
3 jobs for drop-wl-drm-ref in 1 minute and 12 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Review
passed check-commit #10171430

00:00:11

 
  Prep
passed debian:buster@container-prep #10171431

00:00:23

 
  Build
passed build-native #10171432

00:00:37