Revert "drm/i915: re-order if/else ladder for hpd_irq_setup"

We now use ilk_hpd_irq_setup for all GMCH platforms that do not have
hotplug. These are early gen3 and gen2 devices that now explode on boot
as they try to access non-existent registers.

Fixes: 794d61a1 ("drm/i915: re-order if/else ladder for hpd_irq_setup")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201127145748.29491-1-chris@chris-wilson.co.uk
(cherry picked from commit e5346a1f)
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/i915_irq.c

@@ -4242,18 +4242,21 @@ void intel_irq_init(struct drm_i915_private *dev_priv)
 	 */
 	dev_priv->hotplug.hpd_short_storm_enabled = !HAS_DP_MST(dev_priv);
 
-	if (HAS_PCH_DG1(dev_priv))
-		dev_priv->display.hpd_irq_setup = dg1_hpd_irq_setup;
-	else if (INTEL_GEN(dev_priv) >= 11)
-		dev_priv->display.hpd_irq_setup = gen11_hpd_irq_setup;
-	else if (IS_GEN9_LP(dev_priv))
-		dev_priv->display.hpd_irq_setup = bxt_hpd_irq_setup;
-	else if (INTEL_PCH_TYPE(dev_priv) >= PCH_SPT)
-		dev_priv->display.hpd_irq_setup = spt_hpd_irq_setup;
-	else if (HAS_GMCH(dev_priv) && I915_HAS_HOTPLUG(dev_priv))
-		dev_priv->display.hpd_irq_setup = i915_hpd_irq_setup;
-	else
-		dev_priv->display.hpd_irq_setup = ilk_hpd_irq_setup;
+	if (HAS_GMCH(dev_priv)) {
+		if (I915_HAS_HOTPLUG(dev_priv))
+			dev_priv->display.hpd_irq_setup = i915_hpd_irq_setup;
+	} else {
+		if (HAS_PCH_DG1(dev_priv))
+			dev_priv->display.hpd_irq_setup = dg1_hpd_irq_setup;
+		else if (INTEL_GEN(dev_priv) >= 11)
+			dev_priv->display.hpd_irq_setup = gen11_hpd_irq_setup;
+		else if (IS_GEN9_LP(dev_priv))
+			dev_priv->display.hpd_irq_setup = bxt_hpd_irq_setup;
+		else if (INTEL_PCH_TYPE(dev_priv) >= PCH_SPT)
+			dev_priv->display.hpd_irq_setup = spt_hpd_irq_setup;
+		else
+			dev_priv->display.hpd_irq_setup = ilk_hpd_irq_setup;
+	}
 }
 
 /**