drm/i915/gen8+: Do not enable DPF interrupt since the handler does not exist

Looks like DPF was not implemented for gen8+ but the IER and IMR
are still enabled on initialization.

Since there is no code to handle this interrupt, gate the irq
enablement behind HAS_L3_DPF in case the feature gets enabled
in the future.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

drivers/gpu/drm/i915/i915_irq.c

@@ -3796,7 +3796,6 @@ static void gen8_gt_irq_postinstall(struct drm_i915_private *dev_priv)
 	uint32_t gt_interrupts[] = {
 		GT_RENDER_USER_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
 			GT_CONTEXT_SWITCH_INTERRUPT << GEN8_RCS_IRQ_SHIFT |
-			GT_RENDER_L3_PARITY_ERROR_INTERRUPT |
 			GT_RENDER_USER_INTERRUPT << GEN8_BCS_IRQ_SHIFT |
 			GT_CONTEXT_SWITCH_INTERRUPT << GEN8_BCS_IRQ_SHIFT,
 		GT_RENDER_USER_INTERRUPT << GEN8_VCS1_IRQ_SHIFT |
@@ -3808,6 +3807,9 @@ static void gen8_gt_irq_postinstall(struct drm_i915_private *dev_priv)
 			GT_CONTEXT_SWITCH_INTERRUPT << GEN8_VECS_IRQ_SHIFT
 		};
 
+	if (HAS_L3_DPF(dev_priv))
+		gt_interrupts[0] |= GT_RENDER_L3_PARITY_ERROR_INTERRUPT;
+
 	dev_priv->pm_irq_mask = 0xffffffff;
 	GEN8_IRQ_INIT_NDX(GT, 0, ~gt_interrupts[0], gt_interrupts[0]);
 	GEN8_IRQ_INIT_NDX(GT, 1, ~gt_interrupts[1], gt_interrupts[1]);