drm/vram: drop verify_access

Not needed any more.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20191016115203.20095-11-kraxel@redhat.com