drm/vgem: Fix typo in driver feature flags

Fix typo in struct field initializer.

Fixes: 3a6eb795 ("drm/vgem: create a render node for vgem")
Cc: Emil Velikov <emil.velikov@collabora.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181105145428.5590-1-imre.deak@intel.com