drm/i915: only enable hotplug for detected outputs

drm/i915: only enable hotplug for detected outputs

commit b01f2c3a4a37d09a47ad73ccbb46d554d21cfeb0 upstream.

This patch changes around our hotplug enable code a bit to only enable
it for ports we actually detect and initialize.  This prevents problems
with stuck or spurious interrupts on outputs that aren't actually wired
up, and is generally more correct.

Fixes FDO bug #23183.

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>