drm/i915: Reject commands that explicitly generate interrupts
The driver leaves most interrupts masked during normal operation,
so there would have to be additional work to enable userspace to
safely request/receive an interrupt.
v2: trailing commas, rebased
Signed-off-by: Brad Volkin <bradley.d.volkin@intel.com> Reviewed-by: Jani Nikula <jani.nikula@intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>