UPSTREAM: drm/virtio: Replace drm_dev_unref with drm_dev_put

This patch unifies the naming of DRM functions for reference counting
of struct drm_device. The resulting code is more aligned with the rest
of the Linux kernel interfaces.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: http://patchwork.freedesktop.org/patch/msgid/20180716074940.8691-1-tzimmermann@suse.de


Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit eec97cd3677d92a01218b771f35436ea6141e933)
Signed-off-by: Greg Hartman <ghartman@google.com>
BUG: 139386237
Change-Id: I0a2d6876fe60ea14052812a4f7de91372dd29c06