vulkan/wsi/display: don't report support if there is no drm fd
This partially deals with mesa/mesa#4688 Signed-off-by:Lionel Landwerlin <lionel.g.landwerlin@intel.com> Cc: mesa-stable Reviewed-by:
Adam Jackson <ajax@redhat.com> Part-of: <mesa/mesa!10430> (cherry picked from commit 6b61fbca)