drm/vmwgfx: respect 'nomodeset'

commit 96c5d076f0a5e2023ecdb44d8261f87641ee71e0 upstream.

Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com&gt;.>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>