drm/i915: Fix hotplug interrupt enabling for SDVOC

A broken conditional would lead to SDVOC waiting upon hotplug events on
SDVOB - and so miss all activity on its SDVO port.

This regression has been introduced in

commit 1d843f9de4e6dc6a899b6f07f106c00da09925e6
Author: Egbert Eich <eich@suse.de>
Date:   Mon Feb 25 12:06:49 2013 -0500

    DRM/I915: Add enum hpd_pin to intel_encoder.

References: https://bugs.freedesktop.org/show_bug.cgi?id=58405
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
[danvet: Add regression note.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_sdvo.c

@@ -2793,8 +2793,10 @@ bool intel_sdvo_init(struct drm_device *dev, uint32_t sdvo_reg, bool is_sdvob)
 	/* Only enable the hotplug irq if we need it, to work around noisy
 	 * hotplug lines.
 	 */
-	if (intel_sdvo->hotplug_active)
-		intel_encoder->hpd_pin = HPD_SDVO_B ? HPD_SDVO_B : HPD_SDVO_C;
+	if (intel_sdvo->hotplug_active) {
+		intel_encoder->hpd_pin =
+			intel_sdvo->is_sdvob ?  HPD_SDVO_B : HPD_SDVO_C;
+	}
 
 	intel_encoder->compute_config = intel_sdvo_compute_config;
 	intel_encoder->disable = intel_disable_sdvo;