6 bytes seems to be a reasonable default so far, but for the desperate
it's worth exposing this.

[airlied: change include to module.h for this]

Bugzilla: https://bugzilla.redhat.com/582559Signed-off-by: NAdam Jackson <ajax@redhat.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>