drm/i915: Don't pretend SDVO hotplug works on 915

915 doens't support hotplug at all, so we shouldn't try to pretend
otherwise in the SDVO code.

Note: i915 does have hotplug support in hw, we simply never enabled it
in i915.ko: There's only one hpd bit for all outputs, so not worth the
bother to add this special case for this rather old platform.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
[danvet: Clarify that only i915.ko doesn't support hpd on i915g.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_sdvo.c

@@ -1617,6 +1617,9 @@ static uint16_t intel_sdvo_get_hotplug_support(struct intel_sdvo *intel_sdvo)
 	struct drm_device *dev = intel_sdvo->base.base.dev;
 	uint16_t hotplug;
 
+	if (!I915_HAS_HOTPLUG(dev))
+		return 0;
+
 	/* HW Erratum: SDVO Hotplug is broken on all i945G chips, there's noise
 	 * on the line. */
 	if (IS_I945G(dev) || IS_I945GM(dev))