drm/i915: disable the interrupt hotplug for integrated TV output

Otherwise, I'd get stuck in a loop where (afaict) output scan would
trigger a TV interrupt, which would trigger a scan, etc.  TV load
detection not being the fastest thing in the world, X would process
requests very slowly.

https://bugs.freedesktop.org/show_bug.cgi?id=24404



Signed-off-by: Adam Jackson <ajax@redhat.com>
Acked-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>