drm: Introduce drm_dev_set_unique()

drm: Introduce drm_dev_set_unique()

Add a helper function that allows drivers to statically set the unique
name of the device. This will allow platform and USB drivers to get rid
of their DRM bus implementations and directly use drm_dev_alloc() and
drm_dev_register().

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
(cherry picked from commit ca8e2ad71013049bc88a10b11d83712bfe56cdd4)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>